Can I use later seat belts on an earlier car?

MGF/TF appears to have used three different long side seat belts over the years, and two different short side stalk tensioners.  The Early and middle year cars used the same latch/stalk short end, but had different part numbers for the long side seat belts.  

I have an earlier car that needs new long side seat belts.  The middle year seat belts are significantly cheaper than early seat belts.

Has anyone used middle year belts in an earlier car?  

Thanks, John

As far as im aware there were only 2 types of seat belt receiver stalks (aka pretensioners). The early one was common to the Mk1 and Mk2 F plus the Mk1 TF, (any car that had the original Lucas square fob (usually upto 53 plare). These had a red electrical plug for the SRS. 
  The later type was for Mk2 TFs and had a yellow plug. (Mk2 TFs had the later Pektron electrics and oval key fob )

For the seatbelts themselves there was one type for the Mk1 F and then a later one that is for the Mk2 F and all TFs.  I am assuming the seatbelt design was changed at that point to accommodate the changes to the interior layout (to work around the position of the rear speaker bar and different seats).

Given the 2 parts did not change at the same time there should be uniformity between the buckles. 

Note that the stalks/ pretensioners are handed but the seatbelts are not.