The display assemblies should be the same:
http://www.ifixit.com/MacBook-Parts/MacBook-Air-Display-Assembly/IF188-001
The upper case is compatible between some 1.6 and 1.86 models:
Apple part# 661-5072
http://www.ifixit.com/MacBook-Parts/MacBook-Air-Late-2008-Mid-2009-Upper-Case-with-Keyboard/IF188-023
But I don't think that part# 922-8315 for the earlier 1.6/1.8 is compatible with the 1.86
http://www.ifixit.com/MacBook-Parts/MacBook-Air-Original-Upper-Case-with-Keyboard/IF188-002