had same trouble on 4440.  Motor  was put in tractor new in 1995.   They have had nine pages of updates on this motor and gasket,bolts etc. combination. going by the serial number of the engine the dealer should get the right gasket and bolt kit. Can't use newer special bolts in and older engine as others said it will pull the threads.   Deere should be able to get exaxctly whats needed,the gasket and bolt set we used came with it's own instructions.

  Do have the pages of updates but with the scanner here down can't get them to you. I got them from deere when I was having trouble.  Some one from engineering was able to look up the engine and it's history.  was impressed, found out the guy that sold it was at least telling the truth about it.