JP5s originally had tip tanks when built - they were removed when the aircraft had the avionics upgrade (VOR/DME) to become the JP5A.
The JPs on LLADTS (Low level and Air defence Training Sqn) were unofficially referred to as JP5Bs and were in reality a mixture of original JP5s and JP5As with the tip tanks put back on (the dead giveaway for the latter was the fact that they had the nose strakes).
IIRC they were all fitted with twin DME.
In addition to Mad Bob's post, the Strikemaster had the more powerful Viper 535 engine with an extra compressor stage (similar to the Viper 301 fitted to the Dominie).