trans/t-case swap

[Jacks'72K5]

According to the spec sheet, my 72 K5 is running the TH350, 2.52:1, with the NP 205, 1.96:1. I have a 700R4, 3.06:1 attached to a NP 208, 2.61:1. Am I going to run into any major problems swapping these two sets? If I understand the ratios correctly, this will drop my final drive ratio by 1.19:1. Am I correCT?

The 700R4 is from a n 84 6.2L, does that have a different bell housing pattern than the 350?

 

[76zimmer]

According to the spec sheet, my 72 K5 is running the TH350, 2.52:1, with the NP 205, 1.96:1. I have a 700R4, 3.06:1 attached to a NP 208, 2.61:1. Am I going to run into any major problems swapping these two sets? If I understand the ratios correctly, this will drop my final drive ratio by 1.19:1. Am I correCT?

The 700R4 is from a n 84 6.2L, does that have a different bell housing pattern than the 350?

your final drive would drop by the .76 that the 700 has for OD.
the final on the T350 is 1:1.
those would be in high range.

if your looking at low range low gear, that would be the 1.19.

I believe the bellhousing is the same, but will let 6.2 guys tell you for sure.

 

[Jacks'72K5]

Sorry, I did mean low gear, low range. Final drive doesn't matter. This is a trailer queen and will probably never see highway speeds again.

If I understand gearing the way I think I do, will this be the same as dropping my axel gears from 3.83 to 5.02 when I am in low, low? Am I correct?

 

[Speedo]

2.52 x 1.96 = 4.93 ............... 4.93 x 5.02 = 27.75
3.06 x 2.61 = 7.99 ............... 7.99 x 3.83 = 30.60

More probable would be, 7.99 x 3.73 = 29.80, since 3.73 is a common axle ratio. If that is the case then 29.80 / 4.93 = 6.04.

Gus

 

[diesel4me]

The diesels used the same bellhousing pattern as all straight 6 and V8 gas Chevy engines..no problems there..you'll probably need custom driveshafts made though,since they tranny and trasfer case wont end up in the same place as a NP205/TH350 would..crossmember will need to move too most likely..

 

[onetonbb74]

the torque convertor and governor in that trans is for diesel only...

 

[Jacks'72K5]

Drivelines, no prob. Cross member, no prob. What are the problems with the torque convertor and governor, I'm guessing RPM could create problems? Is changing the governor a difficult thing? I can wrench all day long, but never attempted any internal automatic trans repairs.

 

[onetonbb74]

actually the governor is located behind that round cap that is rtv'd on the driver side of trans, easy to change under the vehicle... the torque convertor just needs to be a gasser version...