Will my diff be enough going from 220hp to 430?

73ZED

New Member
Aug 3, 2019
2
Toronto, Ontario Canada
I've been planning for an engine upgrade from a pretty clapped out 350 in my 1973 camaro LT split bumper. It has a Muncie M20 4 speed manual with code P0827A signifying that it's not a numbers matching part, and with the rear diff it's a 10 bolt that I can't seem to find enough numbers on. Maybe tomorrow I'll get under it and check for a different number if there's a recommendation on where to find it, but I've only found a "A308" code on the bottom rear casting wing with a stamped "14" above it on the passenger side. From the photos does this look like an original rear end? And does anybody know where I can find another code stamped on it or know by the photo if this is a 8.5"?

The engine I'm looking at is this: https://blueprintengines.com/produc...m-heads-roller-cam-drop-in-ready-w-pulley-kit

I'll be getting a shop to do the install soon and later in the summer I'm going to spend some time installing a Vintage Air AC system myself since that engine has a compressor included.

The tires I have on them are standard BF Goodrich's vintage style that have little grip, so I'm thinking even with doubling the power the amount of power getting to the road will be the most limiting factor.

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Chevyforever

Veteran Member
Jan 4, 2011
1,478
Ontario, Canada
Looks like the 8.5" version of the 10 bolt. Plenty strong for your intended use. I believe 1973 was the first year for the 8.5" earlier years were 8.2."
 

Twisted_Metal

Administrator
Staff member
Lifetime Gold Member
Feb 26, 2004
31,447
Bloomington, MN
There should be numbers on the front of the passenger side axle tube.

Of course, the gears may have been changed so the numbers don’t mean much.
 

Lowend

Administrator. .a car, a man, a maraca.
Staff member
Lifetime Gold Member
Mar 25, 1999
16,809
San Jose, CA, USA
That's a 8.5" 10-bolt, the squared-off bottom ears is an easy give-away.
The design of the rear end is more than adequate for 500+ HP.
 

CorkyE

Veteran Member
Lifetime Gold Member
Nov 4, 2004
11,781
Ringgold, GA
If you're staying with the standard size tire, you "should" be okay. Like Lowend said, the design is fairly stout. But you have to remember, those internals are 49 years old. I did hit mine with about 650hp on slicks but I had upgraded gears, axles, tubes welded, etc.

Start saving now, you'll need it for tires when you get the new engine installed.
 

73ZED

New Member
Aug 3, 2019
2
Toronto, Ontario Canada
Thanks for the replies, it's a nice restoration on the car but there was no info from the previous owner so it requires a bit more investigative work. The M20 is a 1970 year.

I couldn't find that serial code yet, just using my phone's camera with the car not jacked up isn't ideal for searching, however.

It seems to have really long gears which I would ideally change to be shorter for the stop and go in the city. When I get the chance I'm going to jack it up and check the final drive ratio and see if it has positraction. I think it would be too much to get the final drive changed, I'm trying to not have it become a bottomless pit!
 




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