Good! They should know what to do. The flex plate, crankshaft, and harmonic balancer were balanced as an assembly. You are replacing one of three components, so the replacement part (the flywheel) needs to match the balance of the flex plate.

My understanding is that they attach the flywheel to the flex plate, then balance those together by adding or subtracting weight from the flywheel only. Once the assembly is balanced, then your flywheel is 180 degrees out of balance from the flex plate (the counter-balancing weight on the fly wheel ends up exactly opposite of the original balancing weight on the flex plate). The shop will tell you which orientation the flywheel should be installed relative to the mark you made on the crank.

__________________
Respectfully,
/s/
M. Dillon
'87 124.193 (300TD) "White Whale", ~392k miles, 3.5l IP fitted
'95 124.131 (E300) "Sapphire", 380k miles
'73 Balboa 20 "Sanctification"
Charleston SC