I prepared these Loco’s for an article in Model Rail. They demonstrate the differences within the Class. All are detailed, have lights and are lowered on the chassis. I would say that in the day if we wanted a better Class 37 we had little choice than to detail the loco’s with brass etches and cast parts. Even the detailed models do not sit that well with the latest models but we really had to ‘model’ in those days to get a reasonable result. All Loco’s have Ultrascale wheels with extra pick-ups.
Many of the original loco’s are sold, so this post is not quite as comprehensive as the article in MR.