I would like to install an M21 in a '73 Chevelle with a 454, bench seat and column shifted auto.

The 4 speed and all components came from a '74 Malibu donor car that originally came with a 454, 4 speed, buckets and console. The previous owner had replaced the 454 with a 350.

I removed all the components; trans, bellhousing, fork, flywheel, z-bar, frame bracket, pivot ball, shifter, linkage, pedal assembly, crossmember, driveshaft, etc. I also cut out the trans hump, forward console bracket and inboard bucket seat brackets.

I'm debating whether or not to swap the bench for the buckets and console. Are the trans humps different for bench and bucket seat 4 speed cars? Did bench seat 4 speed cars even have a hump or just a hole cut to accommodate the shifter? I don't think the 350 flywheel will work, but are the bellhousings and rest of the components the same? Will I need to use the crossmember and driveshaft from the 4 speed car? What should I expect/beware of with this conversion?

Thanks,
Donny Moore

You will have to get a 454 flywheel you will also need a pilot bushing I dont know about the tunnel but its hard to imagine they would change the hump between bucket and bench seat cars sounds like you pretty much got it made it would be a tough call for me I had a 74or75 malibu classic wagon with swivel buckets no console (former Boston Police cruiser) very comfortable but I have always wanted a bench seat 4 speed . Good luck MIKE

I have a 76 Cutlass with a FACTORY 5sp that I bought new. It has a bench seat and I really like it, although buckets certainly look better. The car came with a rubber seal and retainer to go around the hole in the floor and a molded plastic adapter that goes on top of the carpet with a chrome bezel and rubber boot for the shift handle. Apparently these cars don't have a shifter hump on the tranny tunnel like the earlier cars had. I have since replaced the factory B-W 5sp with a Richmond 5sp to stand up behind the 455 that replaced the smaller engine. I had to modify the hole in the floor and slightly relocate the other parts, but all the factory floor shift parts were used and it still looks factory except for the Hurst handle. I would think that Malibu and Cutlass floors of the same vintage will be the same or at least very similar. BulkSS is right, you will need to get a 454 flywheel (454 flywheels are ONLY large diameter) because 454s are externally balanced at the flywheel and harmonic balancer. If your bell housing is for the large diameter flywheel (14in), then everything should be a simple bolt on swap. Otherwise, you will need to locate the bigger bell housing and corresponding starter or starter nose. One important tip. For large flywheel applications, the starter nose is different for manual tranny flywheels than it is for autos. An auto starter nose WILL NOT FIT into the bulge of a large flywheel standard tranny bell housing. We found that out the hard way. The starter nose that worked was cast iron, we never found an aluminum nose that would fit. DON'T FORGET THE PILOT BUSHING! Also there is a roller pilot bearing that you can use instead, and I prefer it over the bushing. I just went to look for one on the shelf so that I could give you the Chev part #, but I guess I used the last one. Can anyone give donny the part #? The bearing is also available from NAPA or other parts stores. It's listed for 80s and later Chevys with manual tranny. If you ask for the bearing for a 60s or 70s vehicle the parts person probably won't be able to find it. And when you get that slush box out, throw it in the river!

Bench seat or buckets they had the same floor pan. Driveshaft should work as long as yoke Dia. and trans length are the same, cross member works with both. At least for me it did.

Thanks for the responses. I know that all the '73-'77 GM "A" body cars shared frames, floor and trunk pans. If DZAUTO's bench seat 5 speed Cutlass didn't have a hump, it stands to reason that the Chevelle shouldn't. I've already located a 454 flywheel and the bellhousing I have should be correct, I can't imagine that the previous owner would have changed bellhousings when he replaced the 454 with the 350. Thanks for the tip on the starter. I'll have to locate one because not knowing it was unique, I let it go with the 350. Is the starter still available? I totally spaced out on the pilot bearing, thanks for the reminder.

I'm starting to lean toward the bench seat also. I have only seen one other '73 SS 454 4 speed bench seat car and I really liked the look of the interior, very clean and simple. There's some pictures of it on the Late Model Chevelle Enthusiasts site.

Donny

The rebuilder that does my starters and alternators refers to those style starters as Iron nose starters hope that helps MIKE

Donny, that "type" of starter was literally made by the gazillions. The only thing you really need to be sure is right is the nose. If worse comes to worse, it is available from Chev. But always try your local starter rebuilder first.

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