Are you sure yours are bad? Confirm before replacing. As you found it's an expensive enough part to not replace just as routine maintenance.

The engine shocks do play a part. Particularly with keeping the engine from bucking too much during initial cranking and then at shutdown. You of course need good mounts for the shocks to be effective.

To mitigate the cost, try finding good ones at the pick n pull. Or read the thread linked below about replacing the internal rubber bushing portion of the mount, which is what fails, with home made urethane for much less expense.

http://www.peachparts.com/shopforum/diesel-discussion/314569-cheap-engine-shock-mounts-fix.html