Poll for all you wrench turners
Bolt right in parts, you must be kidding.
As an Industrial Mechanic, Millwright for those who know the trade, I seen just about every part to make Plywood Plants and Sawmills run along with 39 years of wrenching/racing Mopar cars and trucks.
I don't think I can remember a job that all the parts just bolted in. Most parts just need a little massaging to work right and that's the nature of the beast, so break out the tools and get to work.