That looks quite a chunky beast. The gearbox? looks interesting and quite heavy duty; any idea whether it is of Tiger manufacture or a proprietary item?
That gearbox is a Snow Nabstedt 5108L http://snpt.biz/model-5108c/ . It operates without any clutch and can be engaged in forward or reverse at full throttle. And can be thrown from F to R under full throttle. The company is still in business today. This gearbox was used on only two Tiger tractors, the 883 (which I have) and the 552. The 552 was exactly the same at the 883 except it had a 5hp engine and 12" rear wheels where the 883 had a 9hp engine and 16" rear wheels. Tiger called these "automatics". They use 30 weight motor oil for transmission fluid. All other Tigers had regular gear boxes with clutches.
The tractor is very 'beastly'. It's well made and heavy. But it does have some draw backs, like NO BRAKES! None at all. A parking brake was an option but it was for holding on a hill, not for stopping. The rear drive is the weakest part of the tractor. It's a strange ratcher lock drive and when in good condition it works great. The only issue is that when both rear hubs lock up you cannot steer the tractor. Bth rear wheels drive in forward but only the right wheel drives in reverse. The tractor has a ton of umph, cam pull like a locomotive. It's slow and deliberate. But when the rear drive components wearout it's a royal pain. Parts have to be machined to be replaced.
