http://rides.webshots.com/photo/2514251690080251109WlIfzR
http://rides.webshots.com/photo/2210246970080251109QAgPem
http://rides.webshots.com/photo/2598258120080251109fvwbpA

Those are pictures of the 4-53 front mount used in GM trucks from the 60's until 1980. A pair of part number 394136 makes up the set
Not pictured are the steel tubes/spacers that go inside, and they use 1/2" bolts.

You should also look here
http://www.lord.com/Products-and-So...ntrol/Vibration-Isolators-and-Mounts.xml
Lord makes all sorts of engine mounts commonly used by Freightliner, Peterbilt, and I would expect other truck manufacturers as well. The "two-piece mounts" are common.
Somewhere on their website I found a whole PDF catalog of all the mounts, quite helpful. They also have a form so you can give them all the info on your engine and transmission and they can recommend which mounts to use.
Probably have to register, but it's simple and free, well worth it for the info they have available.

Grigg

•1951 GMC 250 in the Project Journals
•1948 Chevrolet 6400 - Detroit Diesel 4-53T - Roadranger 10 speed overdrive - 4 wheel disc brakes
•1952 Chevrolet 3800 pickup
---All pictures---
"First, get a clear notion of what you desire to accomplish, and then in all probability you will succeed in doing it..." -Henry Maudslay-