My master cylinder failed. As far as I know it is the original. The one I got at the parts store is short and fat. My original one was taller. I'm not 100% sure if mine was the original. There is a 10$ core charge and I hate to pile up old junky parts that are worthless. The car is a 70 LS5 Chevelle. Thanks for any advice.
http://farm1.static.flickr.com/155/382043833_caa322e1a0_o.jpg

is that snow I see??

Yes, when my brother-in-law had it he left it sit out for a few years like a doofis. It is the only picture I have of the master cyl.

I'm sure you just bought one just to get by. If it was me, I'd hold on to it. throw it in the trunk. if you think it's the original it's not worth turning it over for $10.

Dave, get the original one rebuilt instead of the parts store units. Brake and Equipment warehouse in Minneapolis does this locally.

Chris, Do can you tell by the picture if it is the original? The new one I have is shorter, but the guys at the parts store claim it is for a 70 Chevelle 454. These guys are pretty sharp but they deal with thousands of different cars. I just wanted to make sure. I guess I could find one at a car show to double check.

Tall and square with bleeders... looks correct to me. Look for BB stamped on the little pad on the front. Last 3 numbers on casting should be 409. Keep it and have it restored.

Dave,that is the correct original. They are easy to rebuild yourself. All you need is the kit,snap ring pliers and a bench top vise :)

I just rebuilt a 409 master cylinder that I picked up a couple years ago. It is very simple to do. I just did mine last night. Rebuild kit was around $33 at NAPA. I've seen 409 cores with the correct BB stamping going as high at $150. Definitely don't get rid of it!

The rebuilt cylinder was cheaper than the kit. I'll save the original for when and if I ever fix up the car..
Thanks for all the help.
Dave

The one the parts store gave you will work but it would never look right on a restored car

If there is rust pitting in the bore when you go to rebuild it you may need to have it sleeved in order to get a good seal and bore that won't chew up the new seal.

Karps Power Brakes http://www.resleeve.com/ did mine with a stainless steel sleeve.
Works great $185 and a two week turn around.
Dave