We are a professional manufacturer of drive shafts and universal joints for farm
tractor in China. The yoke we make are six spline, Lemon and threaded hole. 

The sizes are 1#,2 #,3#, 4 #,5#, 6 # ,4# with slip clutches and 6# with slip clutches:
1) 1 shaft: 
    a) length: 27" - 50"
    b) Six spline ends: 1-3/8"
    c) Up to 30HP tractors
2) 4 shaft: 
    a) Length: 29" - 53"
    b) Six spline ends: 1-3/8"
    c) Up to 56HP tractors
3) 6 shaft: 
    a) Length: 36" - 56"
    b) Six spline ends
    c) Up to 100HP tractors
4) 6 shaft with slip clutch: 
    a) Length: 36" - 56"
    b) Six spline, Lemon and keyway threaded hole 
    c) Up to 160HP tractors at 1,000rpm