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73-87 Chevy _ GMC Trucks => Engine/Drivetrain => Topic started by: Wac93 on March 05, 2014, 07:28:32 pm

Title: 1976 K20 400sbc rear end questions
Post by: Wac93 on March 05, 2014, 07:28:32 pm

I just purchased a 1976 K20 with a 400. I know this is a 3/4 ton truck, but I don't know how to tell what rear end it has.

I was also wondering how hard it is to swap in 4.10 gears. and what posi or locker to buy.

Thank you

Title: Re: 1976 K20 400sbc rear end questions
Post by: pholliday1 on March 05, 2014, 08:00:33 pm

I can guess or you can post a pict and we can tell you in about 5 seconds?

Title: Re: 1976 K20 400sbc rear end questions
Post by: DustyRusty on March 05, 2014, 08:07:51 pm

At least tell us the number of bolts in the differential cover.

Title: Re: 1976 K20 400sbc rear end questions
Post by: Engineer on March 05, 2014, 09:06:19 pm

Is the option label still in the glove box?

Title: Re: 1976 K20 400sbc rear end questions
Post by: Wac93 on March 05, 2014, 11:00:43 pm

I will get a picture and bolt count when I get home for spring break.

Title: Re: 1976 K20 400sbc rear end questions
Post by: Irish_Alley on March 06, 2014, 11:35:54 pm

being a ¾ ton i would almost bet it has 4.10s in it now. every one that i popped open at least had 4.10

Title: Re: 1976 K20 400sbc rear end questions
Post by: pholliday1 on March 07, 2014, 10:26:46 am

That's well and good if its stock? But who knows after all these years and different owners. Really the only sure way is to pop the cover and look at the gears, this will also be able to tell you the type of differential, open, limited slip, locker etc. Kinda like Christmas...........

Title: Re: 1976 K20 400sbc rear end questions
Post by: Wac93 on March 07, 2014, 07:23:07 pm

It's a two owner truck and it has been on a farm its whole life. I will be home this coming weekend and I will see if I can pull it out with all of the snow to get a look at the rear end. Thank you guys for the help thus far.