Yeh, these old pumps are part of the PATS system so the 'RIM' (Remote immobiliser module,part of the pump) needs pairing to the van.

You may need someone with an old Ford WDS system really, as the current diag tool we use IDS has been updated so much it has no or little support for the older stuff. I needed to sort PATS out in a W reg smiley face Transit recently and couldn't - Our WDS went up in smoke the last time it was plugged in

Bit of a pain that they take the support for older stuff, even the 95> Fiestas there's little you can do on them now with the proper dealer tool.

Obviously worth seeing if there's any mobile guys locally who have the kit to do it (mobile locksmiths etc)