K45 is just a heavier duty 6cyl aircleaner, memory is bad in this area but it may only be a heavier air cleaner element. F72 is really just 1-tonner springs from memory but these bolt straight in. F72 also includes stone shields on the shocks on commercials so maybe look for these. Have a read here too:

http://www.mysandman.com.au/forums/s...s+load+package