If you don't want the downtime you can buy 4 rebuilt ones from downey for around $120. They have RC do them and it only costs a little more for the convenience of "borrowing" them and returning your cores. Of course you can just send them to RC engineering, thats who Downey, LCE and most other places use to do them. I think they want $20 or $25 each to do them.

1986 4X4, 1991 22RE, 5.71 gears,ARB Rear, aux fuel tank, 3mm O/S TB/intake, engnbldr cam, LCE header, magnaflow w/2.25 exh. custom 4 color paint job :-P 33X12.5 Goodyear MT/Rs