drbeeper17
New member
- 25
- 13
- 3
- Location
- San Diego, Ca.
So this topic has been covered sporadically in several different posts, but I wanted to make an inclusive one with pictures of the differences between the NP208C and the NP241C.
I recently swapped the NP208 from my 1986 M1008 with an NP241 from an 1989 3/4 ton Suburban. I did this to get a better gear ratio (2.72 in NP241 vs 2.62 in the NP208, better oiling (in the NP241 there is an actual pickup tube that draws oil instead of just the chain slinging the oil as in the NP208, better sealing (the front bolts on the NP208 are tapped all the way through meaning you need some RTV to seal them during install), and better shifting (it is smoother to shift through neutral to 4LO in the NP241). Here are some pictures of it installed.
![IMG_2102.jpg IMG_2102.jpg](https://www.steelsoldiers.com/data/attachments/362/362362-9bfd3f3a1135e31848ae940e7250711a.jpg)
![IMG_2103.jpg IMG_2103.jpg](https://www.steelsoldiers.com/data/attachments/362/362363-17ea0feb8e047fce5d0ab2bfb99ff079.jpg)
![IMG_2106.jpg IMG_2106.jpg](https://www.steelsoldiers.com/data/attachments/362/362364-2ff33734a6f1619fe5af688f42d24cb3.jpg)
The NP241C is a direct swap with the NP208C in our trucks if A) it is passenger side drop, B) it is a 32 spline input, and C) it has a mechanical speedometer. Passenger side drops NP241s are only found in straight axle GM vehicles from 1988 (I've heard some information saying it actually started in 1989) until 1991. So this means K5 Blazers, Suburbans, or classic square body trucks. I believe the 32 spline is only found behind the following transmissions: TH400, SM465, NV4500, and 4L80E. I personally have only found them behind TH400s. Usually if the vehicle is a 3/4 or 1 ton, it will have a 32 spline input NP241. This means K5 Blazers all have 27 spline inputs and will not work. Mechanical speedometers are only found in 1988 or 1989 trucks. In 1990 and 1991 they used VSS.
I recently swapped the NP208 from my 1986 M1008 with an NP241 from an 1989 3/4 ton Suburban. I did this to get a better gear ratio (2.72 in NP241 vs 2.62 in the NP208, better oiling (in the NP241 there is an actual pickup tube that draws oil instead of just the chain slinging the oil as in the NP208, better sealing (the front bolts on the NP208 are tapped all the way through meaning you need some RTV to seal them during install), and better shifting (it is smoother to shift through neutral to 4LO in the NP241). Here are some pictures of it installed.
![IMG_2102.jpg IMG_2102.jpg](https://www.steelsoldiers.com/data/attachments/362/362362-9bfd3f3a1135e31848ae940e7250711a.jpg)
![IMG_2103.jpg IMG_2103.jpg](https://www.steelsoldiers.com/data/attachments/362/362363-17ea0feb8e047fce5d0ab2bfb99ff079.jpg)
![IMG_2106.jpg IMG_2106.jpg](https://www.steelsoldiers.com/data/attachments/362/362364-2ff33734a6f1619fe5af688f42d24cb3.jpg)
The NP241C is a direct swap with the NP208C in our trucks if A) it is passenger side drop, B) it is a 32 spline input, and C) it has a mechanical speedometer. Passenger side drops NP241s are only found in straight axle GM vehicles from 1988 (I've heard some information saying it actually started in 1989) until 1991. So this means K5 Blazers, Suburbans, or classic square body trucks. I believe the 32 spline is only found behind the following transmissions: TH400, SM465, NV4500, and 4L80E. I personally have only found them behind TH400s. Usually if the vehicle is a 3/4 or 1 ton, it will have a 32 spline input NP241. This means K5 Blazers all have 27 spline inputs and will not work. Mechanical speedometers are only found in 1988 or 1989 trucks. In 1990 and 1991 they used VSS.
Attachments
-
79.2 KB Views: 166
Last edited: