X10 - PIRs - MS13 and MS14

[Robin <.@.>]

'afternoon.

I'm in the UK, and I'd like to connect some external wireless PIRs into
my home network. Unfortunately, there is a dearth of X10 compatible
devices because the frequency of the MS14 (external PIR) is restricted
to military use (!).

Given that the MS13 (which is available and legal in the UK, but is
really for indoor use) looks very similar to the MS14, is it possible to
dismantle the innards of the MS13 and put them in an MS14 case?

Thanks & regards
  Robin