The original GM part number for the bearing of 142260 comes up on ebay a couple times.
As well, for cross reference purposes, here is a link to the NSN for subject bearing, along with other part numbers (and the code for the manufacturers) of the same bearing.
http://www.dlis.dla.mil/webflis/pub/...4596&newpage=1
Some examples are: EMERSON POWER TRANSMISSION CORPORATION
ROLLWAY BEARING pn UM1305B108
CNH INDUSTRIAL A18182
MERITOR 1228H268 or 2338N580
The NSN page also gives the GM part number of 7451442, which on ebay leads you to these:
http://www.ebay.com/itm/GMC-roller-b...item1c4e05e032
The dimensions he gives are somewhat off, but they are a hyatt 1206, are in Quebec Canada, he has plenty, and they are $6 each.