Can someone tell me the difference between the Fuchs 16 x 7 & 16x 8 with part # 911. 361.020 .42, 911.361.45 vs the 16 x 7 & 16 x 8 with part # 911.362.115 and 911. 362.117?

I don't have a PET in front of me but, given the years the 16's were made I'd say you have to look at what the 361 vs. 362 numbers relate to. More than likely 911 vs. 944 offset. 341, 351, 361 type numbers have always been suspension numbers I believe. You'll find them on wheels, struts etc...

According to my info:
911.361.020.42 - 8 x 15, 10.6mm ET
911.361.020.43 - 6 x 16, 36mm ET
911.361.020.44 - 7 x 16, 23.3mm ET
911.361.020.45 - 8 x 16, 10.6mm ET
911.362.119.00 - 9 x 16, 15mm ET
951.362.117.00 - 8 x 16, 23.3mm ET
951.362.115.00 - 7 x 16, 23.3mm ET

HTH

pretty sure the later set were produced for the 944 series. They looked the same from the outside as far as the dish depth etc but the lug holes were recessed an extra 13mm, looked kind of funky.