Getting a bit fed up now of replacing front sensors, the only ones that aren't genuine wabco, had to destroy the fronts doing the ball joints nearly 2 yrs ago and fitted new aftermarket ones at the time. Doesn't seem to matter where I get them from or how much I pay they just don't last. Looking at a front and rear pair I have in stock they look identical except the cable length is an inch or so different but I'm confident that wouldn't be a fitment issue but is there another issue as to why rears can't be fitted to the front on a 2001?
Used wabco rears seem to be easy to get, fronts not so.

No problem at all, they are all the same except for the cable length and location of the grommets. One of the rears on my Ascot died and, as it is pre-97, has the really long cables that run along the axle. I got a used Wabco, chopped the plug off and soldered it to the old cable, works perfectly.

Brilliant news. Ta muchly!

Had a bit of luck and scored 2 wabco fronts off a breaker. Got to fit them still to check they are OK.

Fitted them and all good except they were rears not fronts, not enough rubber trumpets to locate. Ebay sensor robbed of its rubbers so that sorted that.