Part No 9790378 and 9790377

[joeskylark]

Hi all. Im installing a new rear from a 71 GS into my 70 skylark convertible. My assembly manual shows a spacer part no 9790378 and 377 for GS 455. It mounts where the rear jounce bumper at the control arm mounting point. Is this an essential part? Does anyone have a pair?

 

[LARRY70GS]

Hi all. Im installing a new rear from a 71 GS into my 70 skylark convertible. My assembly manual shows a spacer part no 9790378 and 377 for GS 455. It mounts where the rear jounce bumper at the control arm mounting point. Is this an essential part? Does anyone have a pair?

I believe you are referring to the braces that were used on big block and maybe all GS's. They tie together the upper and lower rear control arm mounting points to strengthen the whole area.

These are the original pieces,

https://www.ebay.com/itm/1969-1972-...ash=item4d7765d51d:g:ZHAAAOSwyLdbNAOA&vxp=mtr

These are better quality tubular aftermarket products that do the same thing with even more strength,

https://www.ebay.com/itm/UMI-Perfor...ash=item2ea5927b5c:g:xuUAAOSw8d9UwUdr&vxp=mtr

Yes, they are a good idea if you are anticipating higher loads of racing at the track or use of sticky tires.

The 1971 rear should be an 8.5 10 bolt, great rear. Just need to shorten the drive shaft.

 

[TODD]

Buick used the 9790377/8 spacers on the '68-72 GS400 and GS455 but not the GS350. The spacers limit the amount of rear-end squat during hard acceleration. If your car still has the 350 motor, it should do fine without the spacers.

The only other parts book listings for the 9790377/8 spacers appear for '68 Chevelle wagons and El Camino. Buick used similar spacers in the regular A body wagons '68-72 under part numbers 9793636/7. SportWagons did not use the spacers. The 9793636/7 nos eventually superseded the other numbers and covered the applications in most all GM '64-72 A body cars having rear axle bumper spacers. That gives some good leads in finding spacers in salvage yards.

 

[joeskylark]

I believe you are referring to the braces that were used on big block and maybe all GS's. They tie together the upper and lower rear control arm mounting points to strengthen the whole area.

These are the original pieces,

https://www.ebay.com/itm/1969-1972-...ash=item4d7765d51d:g:ZHAAAOSwyLdbNAOA&vxp=mtr

These are better quality tubular aftermarket products that do the same thing with even more strength,

https://www.ebay.com/itm/UMI-Perfor...ash=item2ea5927b5c:g:xuUAAOSw8d9UwUdr&vxp=mtr

Yes, they are a good idea if you are anticipating higher loads of racing at the track or use of sticky tires.

The 1971 rear should be an 8.5 10 bolt, great rear. Just need to shorten the drive shaft.

No the part is a spacer which seems to raise the jounce bumper a few inches. Todd in the next reply has the right one. My car was a 350 but a fresh 455 is going in. Just a street car and sleeper with an occasional test and tune. Ill keep looking. Thanks