Tranny swap help

[cochino12]

So the tranny in my k5 now is a th350 with some sort of adaptor to bolt it up to np208, the blazer originally had 700r. The tranny is ready to die and I dont know what will bolt in easiest now. I was told a 700 would just bolt in no big deal and I was also told a th350 wont work easily because the adaptor is attatched to this tranny? I want to have the tranny built while still driving this one around. Can anyone tell me what kind of adaptor this is? I hope that makes sense

[Grim Reaper]

VERY odd.
I know that some sort of adaptor has to be used in the swap. The output shaft was longer on one of them but I could have sworn it was the 700 that had the longer shaft but maybe I got it backwards. Check Advanced adaptors site and see what they list.

[cochino12]

I am a little confused still one of the guys on CK5 said

"that looks like the adapterfor a 2wd th350 so you can bolt a np208 to it. The shaft on a 4wd th350 is not long enough so you have to use a 2wd th350 with both those adapters"

"The ony 2wd tranny that will work must have the short output shaft. There were several 2wd tranny's and some had longer output shafts. The short shaft version will not bolt to your setup without cutting approx 7/8" off of the end end of the shaft. The adapters I have seen were designed to replace the 700r so that there was no change in length = no modification to driveshafts"

Ever heard of that? So am I correct in saying that as long as l find a 2wd short shaft th350 it should bolt right in using the existing adaptor?

[hotrodhomi]

Most tranny shops could have it back in a day.. I would go that route.

[Grim Reaper]

Originally Posted by cochino12

I am a little confused still one of the guys on CK5 said

"that looks like the adapterfor a 2wd th350 so you can bolt a np208 to it. The shaft on a 4wd th350 is not long enough so you have to use a 2wd th350 with both those adapters"

"The ony 2wd tranny that will work must have the short output shaft. There were several 2wd tranny's and some had longer output shafts. The short shaft version will not bolt to your setup without cutting approx 7/8" off of the end end of the shaft. The adapters I have seen were designed to replace the 700r so that there was no change in length = no modification to driveshafts"

Ever heard of that? So am I correct in saying that as long as l find a 2wd short shaft th350 it should bolt right in using the existing adaptor?

My uderstandign is the 4wd TH350 did not have enough output shaft to work with the NP208.
The cut off the shaft is a trick to get a 700R4 to bolt to a TH350 version of the 205 or 203.

I think the guy is right and it makes the most sense. The 2wd TH350 tail housing bolts off. That is a 2wd TH350 and the adaptor makes it work with the NP208.

A late model 4wd TH350 is know as a "K" case. If the case is clean you may see the big K on the side of it. They ground a K by hand into the K case molds. It has a thicker bellhousing and the bell housing has a reinforced bell housing cover that is cast aluminum and held on with 6 3/8's bolts. The cover then had a pair of braces/rods that went up to the motor mounts. If it has a staped steel cover hels in with sheet metal looking bolts then it's eaihter a early TH350 or a 2wd TH350. If it's a TH350C and no better bell housing it is most definatly a 2wd version.

2wd version is not a huge deal with the 208. It's MUCH lighter then the 203 and 205 so the bellhousing is strong enough to handle it in most cases.

Whats wrong with the TH350 you have? Rebuilding them is easy and cheap. Parts for a full rebuild as long as it hasn't done something nastly like blown the sprag is only about $125 and that includes a Reman converter.

[79BIG10]

When we swapped a buddy's tranny Th350 out for a 700r4 we found that same adapter. The truck originally came with a 700r4 then was swapped out later by PO for a Th350. He had to add the adapter to convert it over to the NP208 and then the shafts were still working.