Ok good people. I'm currently in the process of getting the rear end of my 84 squared away. Problems are that it is an open diff, and its a 7.5 10bolt. I do want a posi or an eaton automatic locker. My question is will the stock rear be able to handle 350+ hp? Or is getting a posi for this a waste of money considering its a 7.5 to begin with? What came i. the Firehawks?

 

It's always a dice roll. The 10 bolt has been broken on the street with a factory engine. It's also survived dragstrip use behind engines more powerful than what you have planned.

Don't expect it to last forever. How you drive will determine how long it will last.

Providing you can even find one, the SLP Firehawk came with a very rare Dana44. At one time you could buy this over the counter from your GM dealer. To find one still in good condition, they will be expensive. For a little bit more, you could buy a new aftermarket direct bolt in 9" or 12 bolt.

 

The stock rear can handle 800hp as long as your are not launching it on drag radials or slicks. You can do a bunch of things to strengthen up the stock rear but I have seen them explode with as little as 400 fwhp when launched at the track. I have also seen them handle more then 500hp street driven.

There is a reason why people upgrade to ford 9", moser, and strange rears.

But getting a posi is not a waste. I am running 400hp with the stock posi rear. The posi has been giving me trouble but its original. I dont run drag radials and I dont launch the car from a dig. Im not going to say I dont have fun though.

 

Thanks guys. I do appreciate the info. Unfortunately spending upwards of $2000 on a new rear end wasn't in the plan when I started to build this car. Heck, that's more than what I have in buying the car. So I'll end up finding an Eaton unit for it, putting new bearings in it, and driving it. It's not going to be a daily driver, and I don't plan on honing on it from dead stops. I'll just have to put the rear end upgrade replacement on the back burner for another time. I called Summit and talked to them as well, and they're pretty much telling me the same thing that you people are. Basically that it's a crapshoot on these 7.5" rears.

Thanks people.