Sorry for the wicked late reply, I forgot about your message. Here's a copy/paste of the information I got from Marlin Crawler:
Ok, for any R-series trans that we rebuild, we have a special
treatment. The First gear thrust washer is a weak point, we have our own
Chromolly Thrust washer. We also have a Chromolly Bearing retainer.
Marlin has seen the stock retainer worn out on almost all of the
R-series cores we get, that is why we stopped that problem. They are
fully cleaned, inspected and built better than stock. As for price, a
Fully built trans, with short throw, shipped is $1470.00. If you have
any questions you can call and ask for Angelo, our builder.