I have some further links for you. Look at:
The NMPO is the Dutch micropulling organisation, they pull with gas, glow and turbine engines.
The RCTP is the German micropulling organisation, they pull with gas, glow, turbine and electric engines/motors.
I have also a E-mail adres, from a guy in the Netherlands how builds every part you need to build a puller. Clutches, chassis, drivetrains, crossboxes, rims, and much more...
He builds very nice parts, from aluminium, he has is own cnc mill to do that all. Just be free to ask anything you need to build a tractorpuller. He has also a website but is at this moment down. He is changing this to make a online shop on it. I looking forward to see this and order online.
Look at the picture, i found it on one from the member pages, its a part builded by the above called guy its a complete drivetrain with crossbox to connect 2 time os 15 cc ducted fan engines. WOW