How do I tell if this is 911 or 914?

Get the torsion bar from a front end that you know is a 914/4. If it will fit in the suspension arms, then it came from a /4. If it won't, then it is a /6 or 911 front end.

Either way, it will fit and there are plenty of aftermarket torsion bars out there.

Or, slide out one of the torsion bars and count the splines.

But as Clay already mentioned, the whole assembly is a direct bolt in to the 914 either way.

I don't have any torsion bars to check. But no big deal, it wont be used for a while. It came with elephant rubber bushings so I want to use it on my 6 conversion. I did some research and found out the early 911 stock torsion bars are just 1mm larger than the stock 914 so its still perfect for my road car. thanks guys.

Another difference is on the cross member. The 914 has rounded ends and the 911 has square ends. The A arms will fit in either cross member. The one in the picture appears to have round 914 ends.