I did manage to find a new filter before i got the reply to this thread and the truck is all up and running. FYI for anyone that needs to find a new filter, for some reason the 90 filter for the 4cyl 2wd D21 is very slightly different, have one ready before you take the old one out. The 'new' transmission i bought from the wreckers said specifically to change the filter and gasket and i wasn't going to take any chances.