SM465 Transmission

[Accelo]

I would consider a newer Silverado Manual Transmission like the nv4500 for a replacement. You will get an better gear ratios and overdrive and loose about 100 pounds in the conversion.

[Dashman]

My other truck is an '81 K20 with a 350 that I blue printed and built to have 350 hp and 350 ft-lbs. I also had an SM465. I put over 100,000 miles on that combination hauling out of state many times. The engine was done in by a dime size piece of Keith Black piston that broke off when I moved off the shifter in 3rd gear to change the radio station. It slipped out of 3rd and over revved the engine. That transmission is bullet proof when it comes to torque, at least from a small block it is. You don't have anything to worry about.

I would try to address the slipping out of gear issue because that's something that I heard others experienced also. I went with a friction disk and pressure plate that could hold more torque. I did burn the friction disk a couple of times, but they were rare situations.

I swapped it for a NV4500 to get the overdrive because my truck had 4.11 gear ratio. There was very little difference in the 2 gears between 1 and 4. The 1st gear ratios are nearly identical, and 4th is the 1:1 ratio.