Max_Williamson, Unfortunately the R410's carrier will not work in the R430. The 13th generation carriers changed in design from the prior generations. To add to the issue, the R430 drive carriers are not sold individually by Dell. They only come on new hard drives, not separately.  Hope this helps answer question.  
We are replacing a failed R410 with a R430. Thing is we would like to use the dell SSD disks from the R410 in the r430, We have checked compatibility and it seems the H730P is okay  with the ssd drives (the drives are dell but purchased last year) What we can't get an answer to is if we need new caddies. 
r410 ssd and caddy