Those numbers are pretty much useless. For example 11963 includes the 1a road roller, 4a Massey Harris tractor, 5a London bus, 7a Milk Float and 9a Dennis fire engine. So saying you have a 11963 could mean any of the previously mentioned models which came on the 11963 cards of that release.
There is a casting variation on the #1 road rollers. The first castings were nearly identical to the Lesney castings. The casting modification concerned the support posts for the canopy roof. Early castings had two supports on the front and two on the rear. The modification replaced the thin twin front and rear support posts to one fat single support post in the front and another single fat support post in the rear. I'm not sure when the die was altered but the set featured in the above always comes with the later modified roller with a single fat support post front and rear.
I also wanted to make mention of the "B" series models in the series. The Dennis Fire engine has a front bumper making it a 9b. The ERF ESSO tanker is an copy of 11b and the MGA is 19b. I'm guessing the tanker and fire engine might not have been a deliberate choice. It's easy to confuse the 9a & 9b for one not in the know and perhaps the same confusion came about with the tanker. However, someone made a choice to go with the MGA instead of the TD. I think the TD would have been the better choice (IMHO). I'm wondering if they based the models on what castings they could find or source at that time?
Even in the absence of Ebay, all that was required would have been to make contact with a collectors' club. Plenty in the States, and U.K. Matchbox/MICA in the UK.
Idris wrote:Even in the absence of Ebay, all that was required would have been to make contact with a collectors' club. Plenty in the States, and U.K. Matchbox/MICA in the UK.
Or ask one of the contributors to the 40 years book. It's not like they didn't have the contacts as I bet they were working on the book at the same time these were thought of.