No probs, just remember that whilst the front shaft should be a perfect fit the 43.5mm shaft is approx. 5mm too short for the rear and hence it's probably not a good idea to run it (you'll lose a lot of droop).
However, all is not lost as Yokomo appear to do a longer shaft that should be ideal for the rear:
49.6mm titanium nitride coated shock shaft #YS-5L-2T
Try this link:
http://www.yokomousa.com/catalog/yok_catalog_hires.pdf
The shafts you want are on page 21, in the parts list for the MR4-BC.
