[Richard Ohran]

I pulled the automatic transmission on my 61 Bonneville. I was going to replace it with one from a 61 Ventura 4 door that has fewer miles. But it seems to be a different transmission. The shape of the Bonneville's pan is square while the Ventura's is more trapezoidal. Does anyone have an explanation?

[Richard Ohran]

I pulled the automatic transmission on my 61 Bonneville. I was going to replace it with one from a 61 Ventura 4 door that has fewer miles. But it seems to be a different transmission. The shape of the Bonneville's pan is square while the Ventura's is more trapezoidal. Does anyone have an explanation?

[Floyd Hand]

Richard, The 1961-64 Bonneville and Starchief used a four-speed hydra-matic (jetaway), while the 1961-64 Catalina and Grand prix used a three-speed Roto hydra-Matic (slim-jim) transmission. The big car transmission, ( jet-a-way) is the better trans. of the two. Also parts for the slim-jim is more scarce. Fatsco has parts for both transmissions and his ad can be found in Hemmings. Floyd Hand

[Richard Ohran]

hmmm, time to formulate plan B. I've got a turbo 400 out of a 72 something pontiac. How difficult will that be to install, or would it be better to rebuild the jetaway?

[Floyd Hand]

Richard, Rebuild the jetaway is the easy way. The jetaway is a strong unit when right. The 61 block does not have the holes to mount the starter to the block. The jetaway and slim-jim has the starter mounted to the bellhousings. The 64 and up 389 GTO , and some 64 big car blocks has the pre drilled holes for the block mounted starter. They are plans out there to fab a steel plate where you can use the later transmission with the early blocks. (QUESTION for others) Can the 61-64 blocks be drilled for the starter bolts? Floyd Hand

[Blackcat]

Richard,
The trans out of the bonnie is a better unit. It is the Father to the Th400 trans. It will bolt right up to the orignal engine. Parts are still available to rebuild them. The trans uses a torque converter. The slimjim does not. Finding a flex plate for the slim trans that are not cracked or have major problems is getting extreemly hard. The only problem you might run into is that you will have to dimple the floor pan for clearence. You will have to do it for the 400 trans also. I've been there and done that. Using the 400 trans with the origional engine requires an adapter plate. So far none have been made that I would use. You could use a 64 on up engine and the th400. But, it does cost lots more. Floyd, The 61-64 blocks do not have the cast tab that is drilled for the starter. I have found the cast tab on some 64 blocks. Most are from Bonnies, GTO's And they are cast later in the Year.

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Mr. Z

[This message has been edited by Blackcat (edited 06-14-2000).]

['ol Pinion head]

The old no starter boss/later tranny scenario rears it's head again. Been down that road also. Interesting thing I ran across, several years ago, I picked up an early '63 421 block. It had a starter mounting pad from a later block welded on. The modification was real sanitary as the weld was built up with high nickel rod by someone who knew what they were doing. I showed this block to several oldtime welders & one heavy equipment welder/ fabricator. They all agreed that the welded on tab was on there to stay. I checked the starter mounting area for squareness & for proper dimensions after installing the 421 crank, flywheel, & starter, all was within spec. Anyone else tried this or seen it done? I no longer have that block, but am trying to get it back for my '63 LeMans.

[Floyd Hand]

Blackcat, Yes, Some 64 big car 389 are predrilled and tapped. I have a 64 GP, numbers matching orginal. It does have the starter holes. I talked to several others that have found the same thing. May be a mid year change. Floyd Hand

[Ken K]

I once put a 64 Big car engine in a 65 GTO for a friend, the car was a 4 speed. I knew of the starter differences, the pad to mount the starter was there and there were holes in the pad but when I went to mount the starter the bolts would not go in. The mounting pad holes were there but they were not threaded, the holes had to be tapped. I know you are talking about an automatic trans but if someone wanted to put a manual trans in an old style block couldn't you use a Lakewood style bellhousing?