I have one of those too. It was introduced in 1978 called the GT/16. Really rare tractors. The engines never held up as long as the onans, leading most of them to there demise. The briggs model 40, 42 and 46 was a great engine, after all B&S made them from '76 to 2002. All of them had cast iron cyl liners, some of the later Twin Plus and Diamond plus models had an oil pump and spin on filter.Seems I've seen no mention of 16/6 machines with the Briggs L head horizontally opposed twins? I have two of them with 1977 dated engines.