I believe the difference in the numbers you listed, one is the shackle itself, the other is a whole shackle, pin kit. Both use the same side plates. My '29-'42 and '29-'49 parts books list them the same way. Look at the prices, the #495034 is $ .30, the #603712 is $1.90.
According to the Information packet from GM, ( '37 is what I am looking at ) all trucks up to 1 1/2 T use the same shackles and pins on the front, the 1 1/2 and larger go to a bigger diameter pin and longer pin in the rear only. Shackle length varies from front to back and from other GM cars using the same pin length and diameter, but the design stays the same so swapping side plates for a desired ride height or lack of availability is doable. I have rear shackles on the front of mine to raise it slightly in the front. I bought some NOS aftermarket kits off e-bay with a shorter side plates for the rear to lower it slightly. I found GM used the same pins with the same taper for quite a number of years on a lot cars and trucks, so by choosing the length I wanted, I could adjust the ride height pretty easy.
The kit you listed on Ebay would work just fine as long as you have enough for both sides or could confirm the length. I can't find any information on actual length of the shackles.
Joe
Last edited by Joe H; 10/14/2019 3:40 PM.
