[Bama57]

OK.... I bought this truck off the showroom, so there hasn't been any non Chevy parts installed until last week when I had to replace the hydroboost.

Using digital measuring calipers and depth gauges, I got the following measurements
off a stock Chevy 3500 crewcab.

Distance between the bottom of the hole on the hydroboost to the bottom of the hole
on the master cylinder = 3.500 and the pushrod length = 3.450 inches.

The pushrod might not bottom out in the holes, so maybe the pushrod is snug when the master cylinder is bolted up.

The new Rock Auto hydroboost has a "Genuine GM rebuilt" sticker and it's for my specific truck.... 454 and not four wheel drive.

My 3.45 inch pushrod sticks out past the NEW hydroboost flange, so tomorrow its put the master cylinder on the studs and only tighten the nuts tight enough to find the resistance, measure the gap between the hydroboost and the master cylinder and then see if I can build a spacer.

Sorry for the long read, but I hope this helps someone.

Don in Huntsville



Don