Switching to IGUS bearings won't work in stock trucks. I've gone through a LOT of iterations to get an optimum fitting truck that offers flexibility in bearing selections and not rub against the inside wall of the tower. You will need (4) M3x8 flat heads and nuts. I'll have to look at what was used to connect the arms, I can't remember right now. It's not all thread like the original and uses bolts. I want to say M3x12. Use the stock bolts for the belt fastener. I used some tiny wood screws and melted a hole in the belt for the fastener. This is a work in progress and published early upon request. I hope to get more detailed instructions when I apply to my other MPMD along with more components.
NOTE: MPMD - Belt Fastener 16T v9.stl is for 16 tooth gear conversion which will be another publishing.
I'm sure you can use anything. I used PC+ for that extra rigidity. I printed on a TLM, but it will fit on an MPMD. If you can't print it and want a set, send me a PM.