The Mamod SP3 Meccano engine was always the odd man out in the SP series. It's style never fitted in with the rest of the range. This is my attempt to correct that error.
The SP3A is a combination of parts from an original Mamod SP3 and an SP4. The chassis and engine are from the SP3 and the boiler/firebox/chimney are from the SP4 (both slightly modified so they could be bolted together).
I originally used parts from a MEC1 instead of an SP3. However, it wasn't quite right so I later acquired a spare SP3 and used the parts from that. The photos on the left, except the last, are of the earlier version.