More OEM Minutia, Carpet Backings Options

[StarBear]

@wonkipop
@jeffbowlsby
@van b
@big len
In the midst of finally replacing a few key pieces of my original carpeting. Noticed something somewhat strange (see pics). The backing on the driver’s side (on right) is lighter and kind of light, stiff pvc or something. Stamped with “TSB”. Passenger side backing is black and much more rubbery; not stiff at all. Same situation with the NOS pieces I’m preparing to put in and the NOS passenger mat already in (not in pics).

Any experience, insight, or history on this. These are known (mine) original pieces.
As promised, truly minutia.
Thanks!

Backs of Originals:


Backs of New NOS:

[wonkipop]

@StarBear - found my old left hand drive carpets for comparison.

similar mix.
haven't looked at these for ------30 years!
got a bit of a surprise looking closely after your prompt.
forgot they were a mish mash. probably had noticed this before but long forgotten.

proviso is i can only vouch for these carpets from 1989 on.
but i don't think the original owner before me had any reason to change them.
they are all aged similarly. faded to equal degrees where they were exposed to sunlight and unfaded elsewhere. so.....99% sure its the original installed.

carpet is brown with the white fleck.

black rubberised kind of backing on drivers floor carpet and also little piece that went behind the seat.

clear whitish resin type backing on drivers sill piece, tunnel piece and piece behind the passenger seat. all stamped TSB.

passenger sill and passenger floor piece seem to be a clear resin too, possibly a bit grey but not as thick as the other type and not stamped TSB.

bit i don't have anymore is the piece that went on the passenger footwell wall.
MIA during rhd conversion.

bit from the bin which i recarpeted to match the new unfaded rhd set i made.
its a kind of grey or clear thinner resin backing.