2003 f250 7.3 cylinder6

[Hankins]

Hi, im new to this site a mechanic said my rear main seal is leaking and a piston needs to be changed in cylinder 6 i was thinkin about changing the rear main seal myself how hard would this be also how much would it cost to fix the piston and my hpop is new and the rings are good . Any insight or tips would be helpful thanks