The Caterpillar MD6 Pipelayer was introduced in 1952 and only produced in the USA. This machine was actually already developed because the Trackson company supplied the Trackson Pipe Layer MD6 (pipe layer written separately) based on the Caterpillar D6 Caterpillar Track-Type Tractor.
After the acquisition of Trackson by Caterpillar only the name change into Caterpillar MD6 Pipelayer was implemented. The machine is equipped with a Caterpillar D318 four stroke six cylinder diesel engine. Good for 93 HP power. The maximum lifting capacity of the pipelayer is 26,530lb
Subsequently, Caterpillar has since 1959 developed the Caterpillar 561B, 561C en 561D Pipelayers. Production stopped in 1989 and to date there has been no successor in the 561 series.
A hand built custom resin scale model of the Caterpillar MD6 in 1:50th scale has now appeared from Dan Models from Romania. Unfortunately, to my knowledge, no diecast scale models of the 561 series Pipelayers have been released yet.