Np203 rear output seal

[73K5BlazerSS]

I recently rebuilt my NP203 as well as the stock shifter. I painted the internal parts of the shifter with several coats of graphite paint. I'm curious if the shifter will function longer without grease to attract grit and grime. Anyway my question is about the rear output seal. The kit came with a seal but it's too small. I tried an NP205 seal which was still too small on the OD. The ID is correct at 2.125" but my OD on the case is around 3.37". It's hard to measure correctly with the shaft in the way. Has anyone had this problem?

 

[Chickntrk]

I used a national 473204, but when I look that up it’s not near as big as you need, wonder why your bore is so big? My rear housing looks different than yours, mine doesn’t have those ribs

 

[TJ1978]

I have 2 203's and neither look like that..
Also it's worth the $$ to get off-road designs twins stick.

NP203 Twin Stick Shifter

That's right, we can twin stick the 203! You get rid of the trouble prone and typically worn out factory shifter box and replace it with 2 levers for much more positive gear selection. One lever will shift the case through Hi-N-Lo and the other will control lock or unlock in the differential...

www.offroaddesign.com

 

[73K5BlazerSS]

That is weird. Maybe the rear housing is from a Dodge or Ford?

 

[Chickntrk]

I’m wondering….did this come out of the blazer as is? Or did you have to buy new pieces from somewhere like eBay? I’ve seen some 203 parts listed for sale that the seller had no idea what they were off of

On rock auto the dodge seal is listed as 3.066 OD so that would still be too small

 

[73K5BlazerSS]

It did come out of my blazer. I only replaced one internal part so the case hasn't changed.
I can't imagine New Process would have made that many rear housings for the 203. I think there were some changes throughout the 203s lifespan. Maybe I'll check and see what the later model trucks had for a rear seal.

 

[73K5BlazerSS]

The solution was simple... just go to another auto parts store. Napa had the right seal. Apparently the 73 and 74 NP203 rear seal is a little larger. My parts guys had all the years listed with the same rear seal