4 speed to th400 swap

[joninva]

i have an 82 3/4 ton 350, 4 spd. 4x4. have access to a 454 w/ th400. what do i need to bolt the 400 up to my transfer case? the donor truck is a k30. i can get the crossmembers and column. will my transfer case need to be moved back? if i just go with the 454 and keep my 4 spd, will i just need a bellhousing? thanks

 

[crazy4offroad]

You'll need a TH400-specific NP205. The input shaft of the NP205 is female, which is an oddball compared to other transfer cases.

 

[crazy4offroad]

 

[crazy4offroad]

You may want to look here:
http://offroaddesign.com/catalog/transfercaseparts.htm
"NP205 parts
NP205 input conversion Kit:

Convert your male input NP205 to a TH400 version 32 spline short female input gear. Kit includes new input gear, input bearing and a seal and gasket kit. Requires machine work on the NP205 case to install, the input bearing bore must be enlarged by about 3/8" compared to the small bearing."

incase your search for one doesnt pan out.

 

[nvrenuf]

What years the k30? This will effect which 205 input you need.

As for swapping to a 454 and using your 4spd, the trans is good to go as is you'd only need the correct flywheel for the 454.

 

[bucket]

What years the k30? This will effect which 205 input you need.

As for swapping to a 454 and using your 4spd, the trans is good to go as is you'd only need the correct flywheel for the 454.

If it's an '85 or newer, couldn't a 32 spline np208 also be used? That's what's behind the '82 3/4 ton sm465 that's in the truck already, isn't it?

 

[nvrenuf]

I got my head stuck on the 205.

Yes, the '82 32 spline 4spd will bolt up to a '85+ 208 assuming you have the correct adapter (4spd to -> up to '84 figure 8 pattern vs '85+ round pattern).

The t-case & year of the K30 will will make a difference on which tailshaft the th400 has which will effect which case fits.

 

[joninva]

more info

thanks for the replies. both trucks are 82 models. i think my k20 has the 208 t-case. so it sounds like the th400 from the k30 won't bolt up to the 208 in the k20, right? so if i keep the 4-spd in the k-20, the bellhousing will bolt up to the 454 and all i'd need would be a clutch & flywheel? this truck (k20- 'old blue') is a farm truck with a Hydrabed ( hauls 2 round bales of hay ). would like to have the automatic because of all the forward & reverse shifting moving hay, but i can deal with the 4 spd. don't want to put too much money in it.

 

[nvrenuf]

What t-case is in the K30? Why not swap the th400/t-case assembly into the K20?

Yes, the 454 is a direct bolt up if you find a flywheel. you're clutch will work too but I'd swap in a new one since it'll be apart.