Th400 swap

[towdriver80]

Hi, Ive got a 79 k5. Blew out the front seal on the tranny(th350) bogging yesterday. I have a th400/np203 combo laying around and wondered if it would be a direct swap, or if I would have to make any driveshaft length changes? This th400 has an electric kickdown instead of a cable, any one know if it needs a ground or +12v signal? Any help would be really appreciated. I dont want to waste time dropping and repairing the 350 if the 400 would fit. The engines pushing over 400 horse, and its sitting on 39.5`s, I think its only a matter of time before something more serious blows on the 350.

 

[boz42]

Hi, Ive got a 79 k5. Blew out the front seal on the tranny(th350) bogging yesterday. I have a th400/np203 combo laying around and wondered if it would be a direct swap, or if I would have to make any driveshaft length changes? This th400 has an electric kickdown instead of a cable, any one know if it needs a ground or +12v signal? Any help would be really appreciated. I dont want to waste time dropping and repairing the 350 if the 400 would fit. The engines pushing over 400 horse, and its sitting on 39.5`s, I think its only a matter of time before something more serious blows on the 350.

d-shafts will change for sure. frt will be longer rear will be shorter. 12 volt signal for switch irc.

 

[towdriver80]

Thank you. I Think I will measure the new lengths and go junkyard hopping. I really want to get that th400 in there.

 

[sweetk30]

fill in your profile and location stuff. i live in ny state and might be able to help you.

 

[RustBuket]

Just a thought.... I have no idea if you could this or not but maybe you could hook the elec kick down as normal but u could have a little thumb switch on the wheel or something for those times when she just doesn't kick down when you want.... ?

 

[towdriver80]

Thanks again for the help. I had the front driveshaft from the one ton truck I scavenged the tranny and t-case out of, and it measures up o.k. The machine shop in my town said they could cut the rear shorter for me for $50. Im going to put the tranny in and recheck all the measurements `cause its hard to cut a driveshaft longer. I spent too much on the 39" boggers(15 inch rim), So I dont want to put in the one ton axles(16.5" rim) until I`m ready for the next set of tires. Can I find a custom U-joint that will let me use one ton driveshafts with the 12 bolt axles? I`m not good with computers, where do I click to edit the profile stuff you were talking about?

 

[sweetk30]

go to napa or do a serch in here under ujoints. there was a chart posted a few weeks ago with # on it.


thanks for the profile info. now i can see how close you are to me. good luck.

 

[sweetk30]

just checked and there is a member in your county. and we are going to do a gettogether in late spring or summer. more details in the reginal form. its all there . hope to see you .

 

[towdriver80]

Sounds like fun. Will NY state troopers really let more than two k5`s assemble in one spot?

 

[sweetk30]

hahaha funny. we just had a poker run up here and the sherrifs were giving out tickets and the troppers showed up and kicked there a$$es out and told them to go to hell. thay didnt relize how much money we bring in to the small town every 4-5 times a year in the middle of nowere.