We recently reached out to the guys in Summit Racing’s renowned tech department—the largest full-time staff in the industry—to identify and answer five common tech questions they hear on a consistent basis. With help from Summit Racing’s tech advisors and other industry experts, we’ll answer those questions here at OnAllCylinders. Today’s topic: transmissions.
- Most transmissions will have a 'source serial number' (chassis vin) usually found close to the transmission code. This number will contain division ID #, model year, assembly plant and production sequence (last 6 digits) of the VIN stamped onto the transmission. Example: 19N500001.
- The transmission case has various codes including the casting code and the serial number. The serial number provides the date of manufacture, however, on 1969 and later transmissions there is a letter code at the end which identifies the gear-ratio, which is different on all three Muncie models. An example of the serial number is 'P4D23B.'
- Never seen a Chevy 833 with a 5-bolt bell housing mount myself. I have two 833s from Chevys, one with the standard 4-bolt GM mount, and one with the odd ball 4-bolt mount. GM only lists two different cases: 1) 1981 (GM part number 14039084), which is the aluminum case with the standard 4-bolt GM pattern.
The specific question: “What type of transmission do I have?”
It’s a basic question, but according to Summit Racing technical department supervisor Norm Koval, it’s a topic that comes up quite often among customers. It’s also a key question central to your vehicle’s performance, and it needs answered before you can proceed with a variety of performance or maintenance projects.
We have all the confidence in the world that you’ll be able to distinguish between a basic automatic or manual tranny. Now, with help from Koval and the Summit Racing tech staff, we’ll help you figure out which specific automatic or manual transmission plants your vehicle’s rear wheels.
We’ll start with common automatic transmissions.
Automatic Transmissions
Some transmissions may have a code stamped into their case or a tag riveted to them. According to Koval, the easiest way to identify an automatic transmission, though, is by transmission pan shape. “Almost all have their own shape and pan bolt design,” Koval said. “Some are square; others are shaped like Louisiana or Texas or some other comparable shape.”
We compiled a slide show of specific pan shapes and matched them up to their automatic transmission counterparts. Find your pan shape—and ultimately your automatic transmission—in the images below:
Another way to determine your transmission is by measuring the overall dimensions. The good folks at Summit Racing also provided us with charts for that:
| GM Automatic Transmissions | ||||||
|---|---|---|---|---|---|---|
| Type | 1st Gear | 2nd Gear | 3rd Gear | 4th Gear | Overall Length | Bellhousing-to-Transmission Length |
| TH-350 | 2.52 | 1.52 | 1.00 | -- | 27-5/8' * | 20-3/8' |
| TH-400 | 2.48 | 1.48 | 1.00 | -- | 28-1/4' + | 26-3/4' |
| TH-200-4R | 2.74 | 1.57 | 1.00 | 0.67 | 27-3/4' | 26-7/8' |
| TH-700-R4 & 4L60 | 3.06 | 1.62 | 1.00 | 0.70 | 23-3/8' # | 22-3/8' # |
| 4L60E | 3.06 | 1.62 | 1.00 | 0.70 | 30-3/4' | 22-3/8' |
| 4L80E | 2.48 | 1.48 | 1.00 | 0.75 | 31-1/2' | 30-3/8' |
| *With 6″ (short) tailhousing | +With short tailhousing | #Except Corvette | ||||
| Ford Automatic Transmissions | ||||||
|---|---|---|---|---|---|---|
| Type | 1st Gear | 2nd Gear | 3rd Gear | 4th Gear | Overall Length | Bellhousing-to- Transmission Length |
| C4 | 2.46 | 1.46 | 1.00 | -- | 30-1/2' | 20-1/4' |
| C6 | 2.46 | 1.46 | 1.00 | -- | 30-1/2' | 22 1/2' |
| AOD | 2.40 | 1.46 | 1.00 | 0.67 | 30-3/4' | 22-1/4' |
| E40D | 2.71 | 1.53 | 1.00 | 0.70 | 37-1/2' | 29-3/8' |
Manual Transmissions As mentioned above, modern 5-speed and 6-speed manual transmissions are easy to identify, but older 4-speed transmissions have more variety. While there are no distinctive pans and bolt counts to make transmission identification simple, 4-speed manual transmissions can be generally identified by examining the side profile. Identifying GM 4 Speed Transmissions - General Motors Transmission Identification This resource will be on going, and grow as time permits. This resou Tech Line: 330-898-6989 Toggle navigation Search View Cart Total: $0.
| Chrysler Automatic Transmissions | ||||||
|---|---|---|---|---|---|---|
| Type | 1st Gear | 2nd Gear | 3rd Gear | 4th Gear | Overall Length | Bellhousing-to- Transmission Length |
| A904 | 2.74 | 1.54 | 1.00 | -- | 30-1/2' | 22-2/3' |
| A727 | 2.45 | 1.45 | 1.00 | -- | 34-3/8' | 22-2/3' |
| A518/A618 | 2.45 | 1.45 | 1.00 | 0.69 | 36-7/8' | 24' |
| A500 | 2.74 | 1.54 | 1.00 | 0.69 | 34-1/2' | 24-1/2' |
Manual Transmissions
Manual transmissions are a little bit trickier to identify, so we turned to our friends at Hurst, who have assembled a handy assortment of diagrams to help you positively ID your manual tranny. Click on your standard transmission speed below and match your manual tranny to the external characteristics and diagram notes:
“As you look things over you may notice casting bosses or provisions on your transmission’s tailshaft housing,” Koval said. “Take note of the number and location. Other things to consider: On the main case, where is the inspection cover…is it a side cover or a top cover? How many bolts secure the cover to the main case and is one edge of the cover curved or straight?”
The selector arms will also help you determine the ID of your transmission, according to Koval. “How do the selector arms mount? Are there mounting studs protruding from the side case or are the selector arms secured with a bolt instead?
Using these clues and the diagrams above, you can narrow down the identity of your manual transmission. Once you’ve made a positive ID, your sales rep or tech advisor can steer you in the right direction for transmission replacement components, performance upgrades, rebuild kits, and other items to help harness all your vehicle’s power.
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The purpose of this page is to help you find all the info regarding the NV3500 transmission’s specs and identification in one place. Within the confines of General Motors transmissions, the NV3500 is known as the M50 transmission. If you made your way here because you were trying to figure out what this code meant, you can rest assured your truck was equipped from the factory with an NV3500.
NV3500 Quick Facts
The NV3500 stands for New Venture Gear 3500. It is a 5 speed manual transmission. The transmission was developed through a joint deal by General motors and Chrysler. It entered production in 1993. It can be difficult to ID it for two reasons. The first is that the case is similar to some transmissions that came before it. The second is that it doesn’t come with ID numbers. We’ll get further into that later in the M50/MD5 transmission identification section.
NV3500 Specs
| Manufacturer: New Venture (GM + Chrysler) |
| Production: 1993+ |
| Type: 5 Speed Manual |
| Torque Rating: 310 ft pounds (1993) |
| Synchronization: Fully Synchronized Forward and Reverse |
| Overdrive: Yes, 1 Gear |
| Case Length: Application dependent. S10 is longer than Silverado |
| Outer Case Material: Cast Aluminum |
| Controlled by Computer: NO |
| Weight: 110 lb. With Oil |
Gear Ratios
There were two possible gearing options, and they were entirely dependent upon what truck that the NV3500 was equipped in. For full-size trucks, GM used the wide ratio MG5 version of the transmission. For the smaller S series trucks, they used the M50 close ratio version of NV3500. Here are the ratios for both,
| NV3500 Gear Ratios | 1 | 2 | 3 | 4 | 5 | R |
| MG5 (wide ratio) | 4.02 | 3.21 | 1.49 | 1.00 | 0.73 | 3.55 |
| M50 (close ratio) | 3.49 | 2.16 | 1.40 | 1.00 | 0.73 | 3.55 |
Dimensions
The catch with the NV3500 in Chevrolet and GMC trucks is that the dimensions were different depending on whether or not it was in the smaller S10 or larger Silverado/Sierra twins.
Transmission Fluid
GM recommends that users use GM Synchromesh manual transmission fluid. It is certified to keep your transmission running smoothly between -40 and 300 degrees Fahrenheit.
NV3500 Identification
There are really going to be two different situation you may find yourself in when needing to identify a NV3500 manual transmission. It’s either, “what transmission is in the truck I have now?” or it’s “Is this an NV3500 I’m looking at?”. Well the good news is that it’s not that difficult to ID it in either situation.
If your vehicle is older than 1993, but newer than 1988 and it has a transmission that looks like the NV3500 it’s probably a HM290, which was the NV3500’s predecessor.
RPO Codes
In order to properly identify the transmission that is currently in your truck, use the RPO codes listed below. The main differences in these versions of the NV3500 are the gearing and overall length.
GM RPO Code M50
If you are looking to find out what kind of transmission is currently in your truck, finding the RPO code M50 is proof positive that the factory installed transmission was a NV3500.
MG5- NV3500 Code
If the RP0 code in the glove compartment ends up being MG5, that means that you have the wide ratio version of the NV3500 transmission. It was typically found in the Silverado.
Visual Inspection
Gm 4 Speed Manual Transmission Identification
All NV transmission are a challenge to identify. This is primarily owed to the fact that they don’t use any sort of identification tag. There are certainly a few easy to use clues that the transmission is the NV3500. We’ll cover them here.
The NV3500 uses an aluminum case. It’s two pieces. The bellhousing and main case are one piece, which means that you can’t replace the bellhousing. So what you’ll see is a detachable tail shaft or transfer case. The rest of it will be one solid piece. This is one of the easiest ways to identify this transmission, or at least verify that you are in the right ballpark. Here are a few other items that will help you lock it down.
- Bellhousing is fused to the rest of the case
- Has a single shift rail vs a different rail for each gear
- It has a fill plug high on the passenger side of the front housing
- Drain plug is on the bottom of the housing
- There are no access plates in the transmission
Rebuild-ability
Gm Manual Trans Identification
This transmission is incredibly difficult to rebuild. This owes primarily to the fact that there are no access codes or casting numbers. Since you can’t even be sure which version you are getting into and working in there is tough, transmission builders don’t like messing with it. Also, it requires special tools to complete the rebuild as well.