Edit: the HU was a brain freeze, the HU went on the SP40 and 510, slightly improved versions of the Mini Mac saws.
Most Mini Macs were "McCulloch" MDC by Walbro.
Be warned though, to put a kit in the Mini Mac will require completely disassembling the saw to get at the carburetor, the engine has to come out of the housing. You can find a video by Saw King on you tube describing that operation.
Mark