13415 912 prototype

Spotted this in the For Sale area. Thought it needed more exposure.
http://www.early911sregistry.org/for...ad.php?t=23123

One thing is puzzling me about the various 'prototypes'. The 5 digit VIN distinguishes the 'prototypes' from the production cars. Some of the early 'prototypes' are truely that with far different body construction than the production versions. Do we know how much the later 'prototypes' varied from the production cars? Were the bodies for these 'prototypes' assembled before Sept 1964 when serial production began?

What prompts this line of thought is the apparent production of a 912 'prototype' or two after series production has already begun; it is said that the 912 began production about April 1965 with deliveries beginning in the fall of that year. So, what is the purpose of these 'prototypes' being constructed a year or more into serial production? Were they test mules for some particular purpose?

If 13145 does have a 356 motor installed, might that reveal a much earlier production date? Perhaps a significant number of these 'prototypes' were built well before series production began, and are thus true prototypes. Much later they might have been refinished, or whatever, thus accounting for the later completion dates, paint codes and so on.

Dave, for the records and this interesting topic, there have been much more 901 w 4cyl engines..

13321: engine: S90 4cyl, later 901 6cyl., color white, built 1962
13328: engine: 901, in august 1965 4cyl engine 616/36, built 1964/65, color brown, red engine cover, sold on 4/18/1968
13329: engine: 901, later 4cyl 616/36, built 1964, color: unknown
13330: engine: 4 cyl, engine no.830001, built 1964, color unknown, sold on 10/29/1965
13352: engine: 4 cyl, engine no.813422, built 1964, color unknown, sold on 9/17/1965
300002: engine: 901, later 4cyl, engine no.832060, color signalrot, sold on 5717/1968

Oh, that is digging up some ancient history.
I am firmly of the opinion, now, that this is one of many "VINs" that was a replacement body.
The whole series was intended as a replacement body series for the 356, and later the 911 & 912. The 901 prototypes were assigned numbers out of this series.