Irwin - you've got the shop manual, so you've got the instructions - only way to do a good job on those vent windows is to
take'em out of the truck!!! do'em in place and you'll bugger the paint fer sure or ruin your freshly paid for rubber!
take it slow and easy, and it ain't that hard to get'em out, and workin on them is
much easier on the bench - if yer doin it right, you'll be replacin the channel felt anyway . . . . .
Bill