Series 3 chassis number

Hi, I bought a series 3 88" diesel before christmas and managed to haul it home this weekend. The last owner died several years ago, it has no v5 or number plates, is missing some parts and looking very miserable. I only paid parts/scrap value for it but the chassis could be fixed and and amazingly the engine turns over so could be a summer project. I'm guessing its quite early say pre 1975, would be nice if it was earlier and tax exempt, might spur me on to do something with it. The chassis number is 906-036xx followed by an A (I've omited the last 2 numbers because this is an open forum) Can someone work out the aprox build date from that? or have a known age S3 with a chassis number thats close?

bilco

This site says its a 71-75 88inch diesel so spot on there:

Identification numbers

Does the dash have really large demister vents on top, about a foot and a half wide with visible grilles, or just small slit outlets? Are the rear lights identical size or are the brake/tail ones bigger than the indicators?

I got a project without knowing all the reg details, a friendly motor dealer told me what it was with their trade HPI type account, a public 20 quid style one wouldn't do it. That was the other way round though, I had the reg but not the VIN.

Thanks for the link Rattlegun.
If 906-00001 A would be 1971 and 906-07270 A would be 1975 that could make mine 1973 which would be nice , unfortunately production figures could vary dramaticaly over the time slot so might sway either way. I think the vents are small but I'll need to check that out in daylight to be sure, no plastics left on the rear lights but the metal back plates look the same size . No servo fitted which I think makes it pre 76. I might just apply for a V5 anyway and leave the reg blank or as not known, not much else I can do but it would be nice to know if it's exempt.
I dont think a HPI check would work backwards but I might be wrong.

bilco.