Anyone know what year GM began using...
 

the 4 3/4" lug stud pattern on their rear ends?

I was looking for a 12 bolt, 5 on 5 in the boneyard last week and found an open carrier rear end in a '78 Chevy c/10, however when I measure the lug studs on center, they were only 4 3/4". I was looking for a 5 on 5 lug bolt pattern to match my front end.

Thanks for any help

Re: Anyone know what year GM began using...
 

You measured wrong.
Centre of stud to outside of stud.
Look here.
https://www.wildhorses4x4.com/produc...terns/tech_faq

Re: Anyone know what year GM began using...
 

Thanks for the info.

Re: Anyone know what year GM began using...
 

I hate measuring wheel pattern spacing so I bought a $5 plastic wheel template at the swap meet. Easy to carry and quick for measuring.