Hiball, I've got one disassembled just like it. Differences I've noted over the Walker 93642 is that the fulcrum is cast one piece, not a weldiment like the Walker. The saddle is different and held in place by the pivot pins, not one piece like the Walker, and unfortunately the long saddle pin is longer than the Walkers. I think it is the one HW is selling now as a 93642. Haven't opened the hyd yet, but it appears on the outside identical to the Walker 42. As you know, I'm a novice with limited sampling!
I'd think the casters would be available and don't appear different from the Walker.
Below is a site that sells parts for Lincoln/ Hein Werners. This will give you an idea of the prices but you should check other sites for maybe lower prices. The PHJ casters are imports and the stem is only 9/16" diameter but it has a step at the bottom of the stem to fit the hole of the 93642. In 2009 they used to sell this casters for $9.99.
http://automaticrepairco.com/shop/viewcategory.php?groupid=17
http://www.phjjacks.com/merchant/me...J&Product_Code=P40025-015&Category_Code=ZRWAC
For parts breakdowns check below, it has plenty of drawings for many brands.
http://www.hcrcnow.com/drawings
And check the Craftsman parts breakdowns below.
http://www.hcrcnow.com/drawings/sears-craftsman
Sorry about that. I did not see any answer posted from you about the casters so I offered the links. Next time you may want to post something like "PM sent" so I know you are quoting a part. So how much was it, like $16.00?