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Discussion Starter #1
I have a 93 fleetwood, and I am going to replace my rearend with one out of a 90 fleetwood, with the 307 motor, are they going to be alot differant gearing wise?
 

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1986 Fleetwood Brougham D'elgance
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I assumed or thought the rear end from a 1985 caddy that had the 4100 motor was better then the 307 rear end unless your useing a rear end from a limo or hearse? If you read other peeps old posts and some new ones. People are looking for those or buying the posi rear kits and installing those.


Someone correct me if I am wrong
 

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Discussion Starter #3
Big_Blue said:
I assumed or thought the rear end from a 1985 caddy that had the 4100 motor was better then the 307 rear end unless your useing a rear end from a limo or hearse? If you read other peeps old posts and some new ones. People are looking for those or buying the posi rear kits and installing those.


Someone correct me if I am wrong
I was just curious on the gearing, I plan on reinforcing it so it can handle the weight of the hydraulics, the one I have know is a little bent already.
 

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94 Fleetwood Brougham
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307 cars possibly had the 7.5" rear, where the 93 has the 8.5". 8.5's are pretty strong, and gears are numerous.

But, in my books (1985 and then 1994, so I am limited that for Cad, but GM doesn't change much once they emissions certify), all 307's were 2.56 geared cars, unless you had a towing package which was 3.23. So they are fairly lame for gearing. Now, all HT4100 cars had 3.42's, this would be a great swap. And if you find a high alt HT4100, 3.73's. BUT, all HT4100's are 7.5.

But unless you are putting slicks on, or towing heavy (5000#+), the 7.5" is plenty sufficient. Just don't go racing with a 7.5". It will last, but not as long as a 8.5".

I think most 350 TBI cars were 2.73 geared or 2.93 geared. So you may be heading the wrong way in gearing. Check first. It might help highway mileage, it won't help power at all.

As for bending housings, I would be concerned if you bent a 8.5" already, the 7.5" may not live long either. Might look at seriously putting in a Ford 9in from a 70's full size, or find a Limo 9.5" from a 94-96 Limo. Maybe more years too, but I know 94-96 got the truck 9.5".

509Rider said:
I have a 93 fleetwood, and I am going to replace my rearend with one out of a 90 fleetwood, with the 307 motor, are they going to be alot differant gearing wise?
 

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93 fleet, 95 fleet, 59 impala
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Discussion Starter #6
N0DIH said:
307 cars possibly had the 7.5" rear, where the 93 has the 8.5". 8.5's are pretty strong, and gears are numerous.

But, in my books (1985 and then 1994, so I am limited that for Cad, but GM doesn't change much once they emissions certify), all 307's were 2.56 geared cars, unless you had a towing package which was 3.23. So they are fairly lame for gearing. Now, all HT4100 cars had 3.42's, this would be a great swap. And if you find a high alt HT4100, 3.73's. BUT, all HT4100's are 7.5.

But unless you are putting slicks on, or towing heavy (5000#+), the 7.5" is plenty sufficient. Just don't go racing with a 7.5". It will last, but not as long as a 8.5".

I think most 350 TBI cars were 2.73 geared or 2.93 geared. So you may be heading the wrong way in gearing. Check first. It might help highway mileage, it won't help power at all.

As for bending housings, I would be concerned if you bent a 8.5" already, the 7.5" may not live long either. Might look at seriously putting in a Ford 9in from a 70's full size, or find a Limo 9.5" from a 94-96 Limo. Maybe more years too, but I know 94-96 got the truck 9.5".
Thanks for the help, I guess I will stick to a 93-96 axel especially if they are stronger, it will get reinforced but I would rather start with a better one.
 

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Where did you bend it? Typically drag racing gets the tubes where they go into the cherry. The trucks likely have stronger tubes, maybe a not so hard swap would be a 3/4t or 1t Dana 70. But you would need custom axles, as they are all full floating 8 bolt. And that full floater wouldn't be pretty to look at through the wheels. But it would be a tough!
 

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Discussion Starter #8
N0DIH said:
Where did you bend it? Typically drag racing gets the tubes where they go into the cherry. The trucks likely have stronger tubes, maybe a not so hard swap would be a 3/4t or 1t Dana 70. But you would need custom axles, as they are all full floating 8 bolt. And that full floater wouldn't be pretty to look at through the wheels. But it would be a tough!
It is bending right where the tubes go in, and I think the axels give just a little.
 
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