truck cab rear side window seals too short (both britpart)

bought 2x new britpart side window seals and filler strips for my truck cab as the old ones were perished, got round to fitting them today, laid them in the groove and they are too short, also tried stretching them after they were in a bucket of hot water but that didn't work either.

am i doing something wrong or should i have gone for genuine seals, if so does anyone know the part number?

i am also fitting a new heated windscreen, so should i also go for genuine here as well

here is a picture to explain better

Used several BP windscreen seals over the years and they have always been fine.
Even genuine ones split given enough time but I have not yet experienced that with a BP item (longest one fitted 7-years).

Are the windows original? Just replaced mine and I think they were Britpart (might have been Bearmach) but they weren't too short.

pretty sure they are original, they have the part number and e marking on them

All the seals I've bought so far had about 5" spare so guessing you r got the wrong bit? What's the part number if the seals you've got? Stretching it won't work because it will just retract over time.

got from paddocks CGE500450

does anyone know the part number i need?

You can buy it for about a fiver a meter on flea bay...

do you have a link?

this is the same isn't it?

http://www.ebay.co.uk/itm/221762461911?_trksid=p2055119.m1438.l2649&ssPageName=STRK:MEBIDX:IT

Parts book shows either 330790 (5mm glass) or mwc4773 (4mm glass). Your part number replaces part mwc4772 which is the little kidney glass window seal on hard top/station wagon - either side of rear door.

id nip back to paddocks and ask for replacements, if the replacements come too short then id go with what others have suggested.

As already stated, you ordered the wrong part (hardtop rear quarter-lights, not truck-cab rear quarter-lights). A quick check of the two part numbers comes up with the different items.
Either order up the correct item or buy it by the metre.