Need Parts Help ASAP!!!

[Keith Sturtz]

Have a 1990 Audi TQ 200 just pulled the head and found out it is toast 
need to get a head and have it rebuilt My problem is There are 2 heads 
available to me asap BUT I WOULD HAVE TO PULL THEM problem is they are 
off 1988 5000 turbo and  1987 500 turbo Both Of these have Part # 034 
103 373  and WHO stamped on head My old head is stamped 034 103 373 AA  
AND also Has WHO stamp in other words only difference is Missing AA on 
the 5000 turbo heads .
Please need to know asap if i can use or what is Meaning of AA (is it 
important) . Also If anyone wants to sell me a 1990 200 TQ head at a 
good ( help a poor audi owner out )  price  please let me know i am in 
the bay area.
ALL RE 's Much appreciated