Hi Guys,

I've spent a lot of time reading & learning but now I'd like to hear your thoughts...

I have a '69 Cutlass with a type O, 2.56 open rear end. After much reading I'd love to swap the th350 out for a 200-4r and go with a 3.90 posi but my budget is a little to tight for that right now. So as an alternative I'm wondering if this rear end would be a good purchase for $500?

Ideally, with my th350, I'm thinking a driveable highway ratio shouldn't go too much higher than 3.55 or the revs will drive me nuts. I think this rear end currently has 3.08 or 2.93 gears. Are gear options for this rear end plentiful & affordable? Would they fit or need a different series carrier?

I really appreciate any advice you can provide - this site has been a great resource full of very knowledgeable people!

Thanks,
Mark

 

What gears are in the BOP posi rear?
In my opinion,if you are going to replace the O-axle,with a different type of rear,I would install a 71-72 8.5" 10-bolt,or a 12-bolt Chevy.
You will need to address the driveshaft length if you swap to a different style rear,unless you use the Canadian yoke on the 12-bolt Chevy.The 8.2" and the 8.5" rears will require you to shorten the driveshaft,and then have it rebalanced.Another cost to keep in-mind when doing the whole swap.
Is the 8.2" rear used/as-is or has it been rebuilt? I would not use a 40+ yr-old rear without going through it.The posi units in the 8.2" BOP's are the cone style.It could be fine,or it could be spanked,depending on what it was used in originally.
Tell us more about the rear you are considering for $500.00

 

Do it once, do it right. You'll be much happier in the end, but I guess if you NEED it, isn't it just a little bit more for a posi unit ($250), used set of gears ($85), and install ($225)?

 

I think the BOP posi rear has 3.08 gears though the seller seems uncertain. He also said they may be 2.93.

Based on my reading from this site, I am looking more at the 8.5 as you've recommended.- Brian. I'm in no rush to buy - just saw this one for sale locally.

So I guess driveshaft length will be an issue with any swap - both 8.5 or 8.2. From a $ perspective, I'm not sure that it makes much sense working with the type O that I have. Brian do you have any advice on this?

I don't know too many details on the rear end - it came from a GTO and I think it hasn't been touched really. It most likely would need some tlc.

Though my car is a stock low compression 2bbl now, I plan to "fix" that issue over time. I'd really like to wake the car up as it's pretty lazy off the line. I'd also like to be able to drive on the highway without it screaming! I'm not too concerned about gas mileage as it's a pleasure driver only.

Bomber77, I'm not sure I follow you. Are you suggesting the posi, gears and install in the 8.2 or my type O?

Thanks both for you advice. I'll probably pass on the 8.2 and keep my eyes open for an 8.5.

I'll be sure to post on the newbie forum and introduce myself and post some pics.

Mark