Changing from Standard Tranny to Auto

[BLT-NT-BOT]

I have a 71 blazer that has a standard in it currently but I would like to swap it out for an automatic. The question I have is other than another 69-72 blazer what trans and transfer case and cross member is a direct bolt in if there is one? Im guessing I would also have to have new driveline made.

Thanks in advance.

[cleszkie]

If you currently have an SM465 4 speed top loader tranny (and not the column shift three speed), the a TH350 auto is a direct swap. You will need to change the input shaft on the 205 transfer case to mate it to the TH350, but the overall length of the SM465 and its adapter to the 205 is the exact same length as the TH350. No changes in drive shaft lengths are required. I know this because I recently swapped out my TH350 for an SM465.

[BLT-NT-BOT]

Thanks for the info, I do have the SM465 4 speed top loader. Is the input shaft a common part that is easy to find and how in depth was it to change?

Jothan

[cleszkie]

The NP205 transfer case was mated to a lot of different transmissions over the years, so there are several different input shafts to be had for the NP205. Fortunately, the NP205 is a popular case, and new input shafts are easy to come by. I bought my input to mate the SM465 to the NP205 from an outfit called Northwest Fabrication [(250) 248-6024]. But there are other suppliers also. Paid about $150 for the input shaft. Paid a local shop to clean up, reseal, and install the new input shaft. I think I paid about $400 for that. The NP205 is a simple case to work on, and I could have done the work myself, but just didn't have the time so I farmed it out.

If you were closer, I would give you the 4x4 TH350 that I removed along with all the linkages and pedal assembly. It all worked perfectly when removed. Now it is taking up valuable real estate in my garage!

[ajviper]

Another option is use the 27x10 Spline drive sleeve. That way you can use your original 205 with a TH350. I plan on doing this to my project K20 at some point.
http://offroaddesign.com/catalog/NP205%20Parts.htm

[72 paul]

Cleszkie,thought you had yours hooked to a gear vendors before you swapped.

[cleszkie]

Originally Posted by 72 paul

Cleszkie,thought you had yours hooked to a gear vendors before you swapped.

I did, and I still do. The Gear Vendors overdrive is mated to the NP205 rear output. So before the swap it was TH350/NP205/Gear Vendors. Now it is SM 465/NP205/Gear Vendors.

[72 paul]

Yeah, didnt think you got rid of it.I never found found the adapter for mine, going 700r.Super deal on your offer to BLT_NT_BOT on your trans.Take care.

[Noble1221]

I need to do the same swap next Spring - my wife wants to drive the Blazer. Is the TH350 a 3 speed auto or a 4 speed auto. Going on the interstate may be necessary for us.

great info and thx to all who contribute.

Joe
Cape Cod, MA

[1rippen6]

I may have everything for a swap th350, np205, and linkage for 400 plus shipping will probably be between 100 to 150 shipping through Fastenal. The vehicles I pulled them out of I couldn't drive engines already gone. np205 are pretty bullet proof but the tranny would probably need a rebuild just to be safe.

[cleszkie]

Originally Posted by Noble1221

I need to do the same swap next Spring - my wife wants to drive the Blazer. Is the TH350 a 3 speed auto or a 4 speed auto. Going on the interstate may be necessary for us.

great info and thx to all who contribute.

Joe
Cape Cod, MA

TH350 is a 3 speed auto without overdrive.