I have a '68 with a 400 SB making I guess around 450-500 HP. I am rebuilding the car now and trying to get a list of things I need together, my budget is limited so I have to differentiate between what I want and what I need. The car currently has a 10 bolt 8.5 out of a 2nd Gen TA with 4.10. I have never had any problems with it but the car hasn't ever been able to hook up either. As I will upgrade the rear suspension for better hook-up and switch from auto to TKO 500/600, do I need a 12 bolt or is my current set-up strong enough? It will be a Sunday driver but may occasionally see some heavy acceleration

I have a '68 with a 400 SB making I guess around 450-500 HP. I am rebuilding the car now and trying to get a list of things I need together, my budget is limited so I have to differentiate between what I want and what I need. The car currently has a 10 bolt 8.5 out of a 2nd Gen TA with 4.10. I have never had any problems with it but the car hasn't ever been able to hook up either. As I will upgrade the rear suspension for better hook-up and switch from auto to TKO 500/600, do I need a 12 bolt or is my current set-up strong enough? It will be a Sunday driver but may occasionally see some heavy acceleration

Well I don't know about you but if I had 450-500 HP I'd be using it. If as you say it is a Sunday/occasional blast car a 10 bolt posi should handle it but if your like me I'd need a 12 bolt.

The 8.5 is a good rear and can handle that power. They'll take it better with some aftermarket parts like a better posi unit and better axles. They claim they'll handle near 550-600hp ???

The 8.5 with a stock posi is going to have a hard time living with the manual transmission if you get good traction. I recommend an upgrade to a 30 spline Eaton and a good set of axles.

Thanks for the info. I know a few companies are making 12 bolts that need no mods to hang under a first gen, is that a better route to take if I go 12 bolt or find one that will fit and upgrade the insides? What should I be looking for as far as what will fit under a stock first gen if I don't go aftermarket?

The Moser 12 bolt is a good strong rear end. Prices start at $1900 with an Eaton posi, gears of your choice and c clip axles.

Thanks for the info. I am leaning toward the Moser unit.