The JSO5 might be confusing to some to think that means it is a 505 but it is a standard NA turbo. Do you have the option info located on the underside of the front lid near the latch that Rarly8 refers to that identifies yours as having the 505 option? Peter Morgan has been an published authority for some time but some published data by some have been incorrect. Would be good to get any conflicting info. Does your 88 930 have the other distinguishing differences (930 vs 930SN) mentioned in the previous posts?

I was missing the option sticker on my truck which is the reason why I got the verification from Porsche. I did came across a few 505 factory slant with a JS05 in the vin in the past. Here's one that I recently saw: https://www.ebay.com/itm/1988-Porsche-930-911-Turbo-Slantnose-Original-Condition-38k-Mi/302949455891?hash=item468931d813:g:T6IAAOSwQita0Rq L:rk:7:pf:0&vxp=mtr

Yes, it looks real even tho the books I have say JS05 in 88 is a standard 930. Rarly8 in a previous post mentioned in his opinion Porsche kept sloppy records in some areas so this could be reflective of that. The only thing I can see missing from the photos is the Porsche crest on the steering wheel hub that 88s & 89s ( not 87s ) should have according to published data. Of course that could have been changed at some time or another misstatement in published material.. Appears that many Porsche reference books got the same VIN info wrong. Also has the ZZZ on the front and the non ZZZ on the other body tags. That makes sense as they left the assembly line stamped ZZZ when the tubs were built. Then the VIN tags with other than the ZZZ were affixed depending on other options, destination, and who knows what else, etc.