Installing a rope seal with the engine in the truck will have about a 25% success rate under the very best of conditions- - - - -and that's with the job being done by someone who is very experienced at doing it. Unless your "local mechanic" is drawing Social Security and doing automotive work as a hobby, it's very unlikely that he will have the knowledge or the experience to do it right. I've been pretty successful at replacing only the lower rope seal (in the main bearing cap) and putting a shim made from the thin stainless steel strip that holds the rubber into a windshield wiper between the upper seal section and the block. It's almost impossible to snake the upper rope into place effectively with the crankshaft still in the engine, or to pack it tight enough in there to make a good seal.
Jerry

"It is better to be silent and be thought a fool than to speak and eliminate all doubt!" - Abraham Lincoln
Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt!
There is nothing noble in being superior to your fellow man; true nobility is being superior to your former self. - Ernest Hemingway
Love your enemies and drive 'em nuts!