G3GM
Would you like to react to this message? Create an account in a few clicks or log in to continue.

G3GM 1973 to 1977 A-bodys. Chevelles, Monte Carlos, El Caminos, Laguna, 442, Cutlass, Malibu, GTO, LeMans, Century, Regal, Grand Am, Grand Prix, Sprint, Gran Sport, Can Am, Hurst-olds, and other 73-77 A-bodies


8.5" 28 Spline Detroit Locker VS. GM 3 Series Posi for 80s Build

2 posters

G3GM :: G3 Tech :: Engine & Driveline

Go down

8.5" 28 Spline Detroit Locker VS. GM 3 Series Posi for 80s Build Empty 8.5" 28 Spline Detroit Locker VS. GM 3 Series Posi for 80s Build

Post by relic7680 Sat Sep 14, 2024 6:37 pm

I am wanting to get a posi or locker unit for the 8.5" 28 spline 10 bolt rear in my '76 GMC Sprint. The car is being built as a period mid 80s street machine and will have a 3.42:1 ratio with 275/60R15 rear tires. It already has Yukon 28 spline replacement axles and a freshly built TH350 is in front of it. The car WILL have a 425-450hp 406 small block (currently a mild 9:1 355).

I am considering some 3 series GM posi units on ebay here:
https://www.ebay.com/itm/235263577331
https://www.ebay.com/itm/154649352539
The second listing proclaims to be a stronger design.

I am also considering Detroit Locker part # 187C149A, which sells new from Summit for $1000+. Was a Detroit Locker for my 10 bolt available back in the 80s? How many guys were running them on the street? What are the pros and cons of this setup versus the GM posi units?

I am honestly not very knowledgeable on this topic, though I have done some research. Any help from guys who were running this stuff back in the day would be very appreciated.
relic7680
relic7680
G3GM Member
G3GM Member

Street Cred : 1

Back to top Go down

8.5" 28 Spline Detroit Locker VS. GM 3 Series Posi for 80s Build Empty Re: 8.5" 28 Spline Detroit Locker VS. GM 3 Series Posi for 80s Build

Post by bracketchev1221 Sat Sep 14, 2024 11:13 pm

In the 80’s there was the gm/eaton posi or the Detroit locker. The locker was noisy and rough. But it was stronger and didn’t slip. You could get a higher spring pressure Eaton that would be fine for anything you throw at it on the street.
bracketchev1221
bracketchev1221
G3GM Enthusiast
G3GM Enthusiast

Street Cred : 16

relic7680 likes this post

Back to top Go down

Back to top

- Similar topics

G3GM :: G3 Tech :: Engine & Driveline

 
Permissions in this forum:
You cannot reply to topics in this forum