Hi all! I trailered my 58 Apache home in July and am in the process of tearing it down to restore from the frame up. I have started looking at replacing the existing SM318 with a modern alternative. The tranny will be bolted to a sbc crate. Likely transmissions will be a Tremec TKX manual or a 700R4 auto. I’m beginning to think the existing low hump trans tunnel is gonna need to change. I would appreciate input about this issue so the mod can be made during steelwork if necessary. The SM318 fit easily with the low tunnel.
'58 GMC 100 series cabs had 3 different Transmission Floor Pan Hole Cover options, depending on what transmission was installed. I assume that the Chevy body had the same options. The one for the 4 speed tranny would obviously have a hole for the shifter. Maybe the HydraMatic pan would provide more clearance??
'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.
From experience the “Low Hump” transmission cover will need modifications to fit either conversion.
Martin '62 Chevy C-10 Stepside Shortbed (Restomod in progress) '47 Chevy 3100 5 Window (long term project) ‘65 Chevy Biscayne (Emily) ‘39 Dodge Business Coupe (Clarence) “I fought the law and the law won" now I are a retired one! Support those brave men/women who stand the "Thin Blue Line"! Hug a cop! USAF 1965-1969 Weather Observation Tech (I got paid to look at the clouds)
That cover plate is my existing setup. Only a small hump in the front. It’s the same plate for the original hydromatic supposedly. There is one other GM option for an original four speed tranny
I'm pretty sure the 4 speed cover is no taller. It just has a cut-out for the shifter.
'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.
The Truck Shop catalogue shows a floor pan with a taller hump for a 4 speed on TF trucks. Likely other suppliers have them as well. However, I have no idea that this will work with a later auto trans. Fred
1956 3100 Pickup/Red/350/3sp OD/PS/Disc Brakes 1957 Bel Air Sport Coupe/Red/355/TH350/PS/Disc Brakes 2017 Silverado LT Single Cab SB/Black/5.3/6 Speed Trans 1947 Willys CJ2A w/F-Head engine
You want something flat to mount either shifter to M or A. Hump you will be fighting. That tremec looks like to shifter is too far back for a TF. The 700R4 can use a cable and mount anywhere.
~ BD. "You won't find me in an old folks home" Pioneer Florida Cracker 1958 Apache Stepside 1958 Apache 1/2 ton Panel 1959 Apache 1/2 ton Panel
