Okie Boy. One of the first "cottage Industry' resin vehicle manufacturers. Their kits are not cheap, and sometimes the instructions are a bit vague, but the quality is quite good. They specialised in British vehicles that the mainstream guys won't touch (the big guys think there is no market for them outside England - fools), but have branched out in recent years.
Tracks are often link and length resin, and need to be heated with a hair dryer to provide sag.
Worth a go if you have the cash to spare.