rearend swap

[85montemj]

i've got an 85 monte with a somewhat built 305 and a th350. i want to replace the 2.56 rearend with a better one to get more power and so i can get rid of this one wheel peel. what would be the best choice, keeping price and driveability in mind.

 

[pontiacgp]

that's a preference thing...I had 241 and went to a 342 which I didn't like due to it reved too high for my liking on the highway so I have 308 in the back end now which I like.

 

[Forsaken502]

what's the main use for the car? will it see alot of highway driving?

for a slightly warmed over 305 even a 7.5" will be ok, which is what you have in your car now. Just be on the lookout for a 7.5" posi unit and decide what gears you want to get. An easier option is just to find a 7.5" rear that already has a posi unit in it and change the entire rear. Look for a option tag with G80 on it

 

[406monte]

If you are looking to drive this everyday and aren't really going to be thinking of racing then i would go 3.08 gears like pontiacgp did. I went from a 2.29 rear in my monte and installed a posi and 3.42 gears and loved it. I then started to go more towards the racing route and eventually had to install 3.73 gears due the the converter and all. But, you are far from this route. I wouldgo with the 3.08 gears myself. This will allow you to cruise and ran all day long and this will also give your little sbc a liitle pep to it. IF you go over to www.montecarloss.com and www.maliburacing.com I think they both have 3.73 gears for the 7.5 there for sale. Good luck in the swap.

 

[nycutlass]

3.23 would work great for you .....just a idea

 

[pontiacgp]

just keep in mind that 308 and down use a 2 series carrier and 323 and up use the 3 series carrier...when I put the 342 posi in I was thinking if I didn't like it I'd just drop in the 308 but I forgot about the different carrier so I had to go track down a posi for the 308....and posi's aren't that easy to come across

 

[shotgun]

Proper advice can't be given until more details on the engine, convertor and tire are given.

 

[85montemj]

how would a 3.42 rearend from an 85 firebird hookup? how much modification would be needed?

 

[SLICK79WGN]

it wont work at all in your car you need to look for one from a MC ss 83-84 had 3:42's and 85-88 had 3:73's and posi was a option on them all just look for option code "G80" for posi

 

[jrm81bu]

how would a 3.42 rearend from an 85 firebird hookup? how much modification would be needed?

You could use the gears and carrier from it. But not the whole housing.