I was just checking out a solo spring seat mounting kit fro the old FX's then realised I didnt have two mounting shocks before the hole.

So I go and check my VIN, and it says SA360##96 OR 5A360##96 ( at least 5A corresponds to harley VINS but it means its a GE-750 frame?) 

What could this VIN mean my frame is? It actually looks more like an S than a 5 on closer inspection.

www.wwwildcats.com/harley_vin.htm

SA = sidecar...errmmm.

 Yeah exactly

I've looked the frame over doesnt look anything like other FX frames. Have I got myself some dodgy bike?

Can anyone tell what this frame might be?

Try the VIN decoder

www.motoverse.com/tools/vin/harley.asp

 says it is not 17 digits, and does not decode "vintage" vin numbers

 What do you think, shoudl i keep it or not waste more time and money on it?

  that is not a stock frame at all , it's & aftermarket frame or custom none harley frame,    could have someone's phone number stamped on it ?              even aftermarket frames do not come with a frame number  because they are only sold as a part of a bike not a complete bike as such