Now the GR4 has different engines
Could you enlighten me please as my belief was that the early Tonka GR1s had Mk 101 RB199s. Later GR1s had Mk 103s and these were exactly the same donks used in the GR4s. Only the F3 had Mk 104s.
Luftwaffe ECRs are/were fitted with RB199 Mk.105 engines, some of which we borrowed during GW1.