The Stovebolt Forums Forums The Shop Area Driveline '59 Apache -what was the original tranny with a V8 4speed?

What tranny was original with a V8 4 speed on the '59 Chevy? What rear end was standard if you have this info to. Thanks.

The transmission would be a SM420.

The rear end depends on what series truck. If it is a 3100/3200 (1/2 Ton - 6 lug) it would have a 3.90:1 ratio. If it is a 3600 (3/4 ton - 8 lug) it would have a 4.57:1 ratio. Both are corporate GM rears. A one ton would have something like a 5.12:1 ratio.
Fred

3200 1/2 ton 6 lug. Thanks for info.

It's a 3200 with 283 V8 4speed. I've read the 3.90 ratio is a good one. Are they much trouble to rebuild if needed? Is the tranny in these '59s pretty much bullet proof and are parts available to rebuild them? Also trying to sort out whether to add disc front brakes and power steering or stay stock. Just trying to get it sufficiently safe. Thanks.

Also 59 a posi was offered, and its different than the non posi. If its a spreader type case its the new posi, if its a drop out third member its the old non posi style, but I have one of them with a limited slip unit in it?

I forgot about the posi being available also. The stock 3.90 rear ends hold up well but are not great highway gears. The only other ratio available is a 3.38:1 available from a variety of sources. Some skills are required to set up the gears correctly.
The SM420 is considered bullet proof but all parts eventually wear out. There are parts available as it was a common trans for many years.
Disc brake kits and PS kits are available from various sources also. About $750 for the brake kit including the booster & MC.
About $800 to $900 for the PS when you add in the pump, pulleys, & brackets. labor would be extra of course.
Fred

The Positraction option used a Spicer 45 (similar to a Spicer 44) sourced from the GMC side. '59 was the only year it was used in Chevrolet. The HO33 axle did have a Posi variant, but they didn't come out until '60, and were only made until '62.