I need to replace the steering shaft on my pony tractor, model 13an77tg766. The parts list shows the replacement to be 738-0919B. When I look online I find some places that sell 738-0919A and others 738-0919B. Trouble is some show them as interchangable and other sites do not. There appears to be a difference in the length of the two but I can't find out for sure. In some of the customer ratings people have complained about the part they got being too long or too short. Just trying to stay our of the buy and return loop. Does anyone know the differences between the A and B?