[69 C10 LWB]

I have been looking around and it looks like there is a big difference between the round and square master cylinders. I didnt take a pic of the old one after I took it off either truck but I found a few online. Looks like the square master actually extends through the firewall and the round one sits flush.

The piston on my new master cylinder sits flush with the end of the body but it has a hole bored in the piston and the pushrod sits inside the piston about 1 in.

The difference in pushrod length was only about 1/2-3/4 in even though it looks longer with the extension I made. Most of the extension is threaded onto the old pushrod.