Master cylinder question...

[GMtraitor]

Hi all, I just brought home my first ever non GM vehicle, and I have a lot of questions about it. This seems like the place to be...

I have an ex-firetruck '75 W300 4x4. Truck has a 360 2bbl, NP 445 4 speed, NP 203 T-case, Dana 60 front, Dana 70 rear with 4.88s.

The brakes need some attention and I think the master cylinder is a good place to start. My question is NAPA shows 2 part numbers for a W300 master cylinder. One is for a 4500 lb front axle and one is not. I thought that the 4500 lb front axle was the closed nuckle Dana 70, not the Dana 60 that I have. Which master cylinder do I need? The master for the 4500 lb axle is about 3 times more expensive...

Thanks in advance!

[712edf]

You probably need the more expensive one. The 70 front was dropped in the W200-300 series after 74. It may have been in some W600's after that. Starting in 75 the 60 was the biggest front the light duty trucks had. My 78 W200 club cab has a 60 front and when I went to get a m/c for it I had to the costlier/rarer of the two that were offered.

You are at the right spot!

WELCOME!

bucky

[W_A_Watson_II]

Try cleaning/sanding on the old one to see if it has any numbers. Also is there a piston diameter difference between the two options? If so remove yours and measure the piston.

[Deathdeelr]

Both master cylinders are the same. The truck only came with a front axle rated at 4500 pounds. The cheaper master is a rebuild. Don't get it. Spend the $200 and save your life or someone else's.