New truck - trans oil change and zinc engine oil question

[BikeBro]

Hey guys, I just picked up a '73 c20 with a 454 and turbo 400. I'm going over the whole truck as it has been sitting a while and am curious what the best procedure is for draining the trans, pull pan OR disconnect trans line from radiator and run engine for several seconds (is this safe for trans?) I plan on gett g a new trans oil filter and a new pan that has a drain plug, any specific ones I need or are all turbo 400s the same? Also, motor is 73 and I assume still flat tapper cam, I should add a zinc additive to my regular oil change correct? Thanks guys 👍🏻

[VileZambonie]

Enriched oil or an additive would be in your best interest. Do not run it with the cooler disconnected, the pump isn't designed to work that way. Drop the pan, inspect and clean. Replace the filter and pickup tube o-rings. Replacement pans are readily available online with drain plugs.

[bedwards]

After reading a good bit about ZDDP in the forums, I've been running either diesel 15w-40 Super Tech, or Rotella and lately 10w-30 Rotella T5 in my and in my '59 also.