I have dragged an series 3 gearbox out from the dark depths of the barn, to use on a tdi conversion, I have dismantled it, to find water had been in it, so bearings need replacing, gears I hope will clean up, but, there are no suffix serial numbers on the casings, all casings ( cog box, transfer and 4 wd selector) have 3031 stamped? however the transfer case is stamped 3031xx. have attached photo of the cogbox/trans marks. as you can see there is no evidence of marks being ground off and then re-stamped.
many thanks in advance