I recently a tire shop (Big O ) change my oil and flush coolant. I asked to check source of oil leak .
They found the front and rear main seals had small leaks, and on my 1998 the engine needs to be pulled to perform this service.
Is this true? Or can it be done w/ engine still in truck?
Thanks in advance .

 

Main seals can't be "small" leaks, they are right next to front and rear crank main bearings so will "pump out" oil if the seal is leaking

And no you don't need to pull the engine to replace Main Seals, front main can be done by pulling the water pump, crank pulley and then the front engine cover, also have to loosen oil pan at the front
3.0 has a known issue with coolant leaking from the engines front cover, front main would be replaced when that repair was done

Rear main needs the transmission pulled off/out, so a lot of work, if you have a manual trans the rear main seal should always be replaced when new clutch is installed

Small oil leaks at the front and/or back of engine is most like oil pan gasket, which can require pulling the engine on some models, lol