NP203 Transfer Case Advice

[XRO]

I have an '83 Jimmy with TH350 and NP203 Transfer case. haven't had the truck long and bought at an auction so I don't have much history on it. Lots of minor leaks from the transfer case, but recently the front output shaft seal went out and it will drain a couple quarts over night. I have a complete seal and gasket kit for the case but was just going to replace the front seal for now. Of course I can't for the life of me get the nut off. Did heat and oil with breaker bar and extension and hydraulic floor jack and it won't budge, just starting to strip it.

Regardless, debating options - do I still just try and do this seal, or pull the case out of the truck and have it rebuilt. I don't really have the confidence to completely split the case by myself and do the full rebuild, never been into one , but I also don't know if it would be worth it to pay someone to do it? Might be more cost effective to just purchase a re-manufactured one?

And if I purchased a re-manufactured one is the 203 they way to go or should I look for a different model? All the transmission adaptors, driveshaft lengths and yokes overwhelm me... not sure what to do, any info would be appreciated.

 

[Hogback Fabrication]

Are you sure it's a 203? Last year of those was 79.

 

[XRO]

I'm pretty sure, can't find the at tag on it but all the pics I've referenced match and the adapter to transmission had a number that referenced it was for the 203 - I know it isn't the original motor or transmission either...

 

[Hogback Fabrication]

If it's a 203, just replace the seal. Any work further than that and I would recommend a used replacement or a swap to something else.

 

[sweetk30]

cast iron case ? or aluminum ?

top pic 203 full time .

middle pic fixed yoke rear 205 part time.

last pic sorry small is a part time np208 .

 

[XRO]

It is cast iron, it's gotta be a 203, pic attached...

Tips on getting the nut off? I have an okay 1/2" impact but I don't think it is gonna touch it no matter what. I think I'm going to have to try and do some type of relief cut in it, not much room to work though...

 

[sweetk30]

yep 203 full time .

what nut ?

 

[XRO]

I'm pretty sure it has the part time kit installed...


The front output yoke nut

 

[sweetk30]

shouldn't be that tight on there .

 

[XRO]

I sprayed with wd40 a few times and put some heat on it and hit with the impact but nothin, then went to breaker bar with extension and even floor jack at the end of extension but nothing

 

[mac907]

Plain wd40 will do little for you at loosening a stuck bolt. I read an article a while back that helped me in selecting a penetrating lubricant to break free pretty much anything. To sum it up, among a bunch of brands tested Kano Kroil removed the most torque from the test bolts and was followed very closely by Liquid Wrench. No other over-the-counter brand came close. With Kano Kroil around $15 a can and Liquid Wrench under $5 I now use The Kroil on really sensitive stuff and Liquid Wrench on everything else to save money.

However, the test also found that simply mixing 50% ATF (auto transmission fluid) and 50% acetone worked even better than the Kano Kroil. Good luck, I hope this helps.