Seatbelt question

Hi,just done a deal on a cabby,should be picking it up in the next few days,I was wondering,can a lap belt be fitted in the middle of the back seat? If so where do I get one from? A tin top?
Cheers,Sean 

never seen a cabby that would seat 3 in the rear, everyone ive had has been a 2 seater bench? may be wrong of course

Super early ones, as I've just found out yesterday, do have a full width bench rather than the two pseudo-buckets.  Mine now has a bench in the back thanks to metalblue on here.