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Robert1970C20rstbukt · 09-27-2005, 09:14 PM

67-70 - 1/2" studs
71-72 - 9/16" studs

They made the lip of the drum bigger to fit over the backing plate, at least that's how they are on my 70.

All Eaton rears had smooth drums, no finned ones.

Here's some info out of the 69-70 GM truck parts book:

Ser. 20 (4/WD)............3754300 $23.75 rear

Ser. 20 (Conv.)
(exc. leaf type spring,
L.P. Gas, 396)..............3857752 $22.35 rear

Ser. 20 w/Dana axle......2458493 $23.25 rear(motor wheel 86516-A)

I couldn't find any measurements for brake drums in that book.

09-27-2005, 09:14 PM	#2
Robert1970C20rstbukt Registered User Join Date: Jun 2004 Location: Beeville, Texas Posts: 1,943	67-70 - 1/2" studs 71-72 - 9/16" studs They made the lip of the drum bigger to fit over the backing plate, at least that's how they are on my 70. All Eaton rears had smooth drums, no finned ones. Here's some info out of the 69-70 GM truck parts book: Ser. 20 (4/WD)............3754300 $23.75 rear Ser. 20 (Conv.) (exc. leaf type spring, L.P. Gas, 396)..............3857752 $22.35 rear Ser. 20 w/Dana axle......2458493 $23.25 rear(motor wheel 86516-A) I couldn't find any measurements for brake drums in that book. __________________ RJD 1984 Chevrolet C30 welding truck 454/SM465 1977 GMC C15 pickup 350/TH350 1970 Chevrolet C20 pickup 350/TH400 1970 Chevrolet K20 Suburban 454/TH350 1969 GMC 8500 478M V6/5 spd winch truck