ur-q Control Arms

["Mike Hopton" <mike@genesis-microchip.on.ca>]

     I was bolting the front and rear subframes on to my '83 ur-q when I 
     thought it would be a good idea to check the control arm part numbers. 
     Hmmmm,  apparently  three of the control arms have the same part 
     number 857 407 153B (LR, RF, LF) and the right rear is 857 407 148A 
     (RR)? The VIN of the car is DA900361.
     
     Anyway I had the control arms sand blasted and powder coated so 
     there's no sign of part numbers to check. I did a fairly thorough 
     visual inspection and couldn't find any differences. Does anyone know 
     how I identify the the right rear?
     
     Thanks for all the comments on the Alloy blocks, so the consensus is 
     they do exist and probably were built in quite large numbers (250 
     production according to Phil). I'll try and get over to 4 Star next 
     weekend and check out Frank Sprongl's Audi Sport motor I'd be 
     surprised if it didn't have an alloy block? I'm quite surprised (and 
     disappointed) to hear so many Sports don't have alloy blocks.
     
     Thanks and regards, Mike