Author Topic: Transmission swap  (Read 570 times)

Offline A robs 23

  • Newbie
  • Posts: 10
  • Newbie
Transmission swap
« on: December 26, 2018, 11:29:33 AM »
Hey guys,

I have a TH400 in my 86 K20. Will be swapping the 305 for a 350 shortly and am hoping to swap out the TH400 for an sm465 that I just got my hands on.

Anyone have any experience with this swap? Any parts that I will need for the swap?

Any experience with the sm465? I would like to throw on a gear vendor overdrive as well. Any issues with driveshaft?

Here is the casting from the casting on my sm465, its going from a 2wd to a 4wd so I am guessing I will need adapters for the transfer case?

Sent from my iPhone using Tapatalk

Offline hatzie

  • Site Supporters
  • Junior Member
  • ******
  • Posts: 769
Re: Transmission swap
« Reply #1 on: December 28, 2018, 08:05:10 AM »
2WD SM465 or 4wd?  Not sure if you can use a 2wd transmission with an attached transfer case.

The stock 1986 clutch is a hydraulic setup.  You'll need to source the pedals, clutch master cylinder, clutch master reserviour, slave cylinder, clutch line, and bellhousing from 85-91 CK/RV squarebody rigs.  The pedals have support struts that run from the clutch master bolts to the pedal bracket.
SVC & wiring mans --> Here or My Bucket @
Parts & Illustr Books -->
GMSTG Textbooks-->
Radio Manuals-->

Online VileZambonie

  • Global Moderator
  • Senior Member
  • *****
  • Posts: 17296
Re: Transmission swap
« Reply #2 on: December 28, 2018, 06:13:17 PM »
Why? The 465 is a slug by comparison
,                           ___ 
                         /  _ _ _\_
              ⌠'   [☼===☼]

Offline 1967KaiserM715

  • Site Supporters
  • Junior Member
  • ******
  • Posts: 914
  • 1985 GMC K1500 w/ 6.5 TD
Re: Transmission swap
« Reply #3 on: December 31, 2018, 03:35:06 PM »
2wd sm465 will need a new main shaft (output) to be converted to 4wd, that means a complete disassemble and rebuild.

I believe the SM465 is 2 inches longer then the TH400, driveshaft may work...

If you plan on a gear vendors, just skip the headaches and get an NV4500, you can get rebuilt for the same price, you can also do the NV3500, just depends on how hard you plan on wheeling and towing/working the truck.

My SM465 was amazing, reasonably quick shifts. But is a heavy duty transmission, it will not shift as fast as a slushbox, nor as fast as a little honda. The shifter is also notorious for gaining lots of slop.

Sent from my SM-S920L using Tapatalk

Current Vehicles:1985 GMC K10(Daily) 1991 GMC K2500(Daily) 1975 Beetle(not running) 1985 Mercedes 300D(not running) 1952 M35    1967 M715(not running)
 1986 Chevy K30(under repair)

Offline werewolfx13

  • Junior Member
  • ***
  • Posts: 831
Re: Transmission swap
« Reply #4 on: January 05, 2019, 10:32:06 AM »
I love my sm465, but if you want an add on overdrive, look at a ranger torque splitter instead of a gear vendors unit. It is installed between the bellhousing and transmission, only requires 7.5, and gives you usable overdrive in 2 or 4wd, forward or reverse. That said, the sm465 is a working transmission, and people often swap one in expecting a performance feel, and end up disappointed because its shifts are long throws, shifts have to be taken slowly, and you are essentially driving a grain truck. I love it. Not everyone does.
'83 Chevy c10 Silverado SWB
'76 Chevy k20 LWB 6.5'x8' Flatbed
I know that you believe you understand what you think I said, but I'm not sure you realize that what you heard is not what I meant.

Offline roundhouse

  • Senior Member
  • ****
  • Posts: 1404
  • Newbie
Re: Transmission swap
« Reply #5 on: January 11, 2019, 06:19:09 AM »
If its going to be a daily driver skip the 465 and use a NV3500 or NV4500

My truck had a 465 in it when I bought it and it really sucks for daily driving

I have had a NV3550 in my 74 Bronco for many years and liked it
So I swapped a 3500 in the K10

Offline Smokehouse

  • Newbie
  • Posts: 28
  • Newbie
Re: Transmission swap
« Reply #6 on: February 14, 2019, 12:33:32 PM »
I love my 465 and yes it's like driving a big dump truck but that doesn't bother me. I talked to someone before if you do a nv3500 or 4500 the shifter will not be in the same spot. That it would be like 5 inches or so closer to the bench. I really didn't want to cut my floor up for that so i'm going the gear vendor route so i can tow in overdrive.
You are not that hot to be that bitchy.