If you'd settle for an SM420 in a 3/4 ton GMC here is a picture. I assume Chevy's are the same. But mine doesn't "sit" on the frame. The mount at the front of the engine and the 2 mounts on the bellhousing are the only mounting points for the engine/SM420 package. The only "mounting bolts" for the SM-420 are the 4 bolts that hold the transmission to the bellhousing.
'57 GMC 102, Original 347 V8, HydraMatic, 3.08 rear gear, added A/C, disk front brakes, HEI, AFB carb, '98 Honda Black Currant paint. T-boned and totaled 10/12 '52 GMC 152 Stake Bed, Original 228, SM420, added A/C, HEI, disk front brakes, '67 Chev 3.55 rear gear. Gets used as a real truck.
Maybe a good time to ask, but I'm wondering if my 4-speed transmission in my '46 is a SM420? If so, I can try to get some pictures of it mounted for you.
~ John in Utah 1946 1/2Ton w/4-speed manual transmission w/1960 235 engine Here We Go Follow in his DITY Bay
- If you think about it, it has been one year ago today!
Maybe a good time to ask, but I'm wondering if my 4-speed transmission in my '46 is a SM420?
John - Your pictured 4 speed w/main case casting number 590474 is the SM420 predecessor - GKT-134, otherwise affectionately known as a "crashbox". It's a non-synchronized 4 speed with straight cut gears where the SM420 2nd through 4th gears are synchronized and have helically cut gears (1st and reverse are un-syncrhonized straight spur gears).
~ Dan 1951 Chevy 3 window 3100 Follow this story in the DITY Gallery "My Grandpa Carl's Truck and How it Became Mine" 1966 Chevelle (Wife's Hot Rod) | 2013 Chevy Silverado (Current daily driver) US Army MSG Retired (1977-1998) | Com Fac Maint Lead Tech Retired (1998-2021)
John - Your pictured 4 speed w/main case casting number 590474 is the SM420 predecessor - GKT-134, otherwise affectionately known as a "crashbox". It's a non-synchronized 4 speed with straight cut gears where the SM420 2nd through 4th gears are synchronized and have helically cut gears (1st and reverse are un-synchronized straight spur gears).
Thanks Dan! I heard it was a "crashbox", but I didn't know the official name. I'm guessing my pictures would not help.
~ John in Utah 1946 1/2Ton w/4-speed manual transmission w/1960 235 engine Here We Go Follow in his DITY Bay
- If you think about it, it has been one year ago today!
It's a non-synchronized 4 speed with straight cut gears where the SM420 2nd through 4th gears are synchronized and have helically cut gears (1st and reverse are un-syncrhonized straight spur gears).