None of AIM's “1-75 Series Regular Wheels” catalogue (second printing, 1983), Stannard, or Leake ("Concise Catalogue of 75 Series Matchbox Toys by Lesney" (4th edition, reprinted 2006)) lists any variation not already catalogued by Nick.
Houghton lists a curious “angled” exhaust as variation code 2b-5, but close inspection of the photograph supplied indicates that it is almost certainly the product of damage during the tumbling process.
U.K. Matchbox did not examine the model.
(Thanks to DrJeep for pointing out that I uploaded the wrong draft this morning!
