not in the service manual
So I put the dowl in the old 360 and it stops very close to seven and three quarter inches. the dowl went over 10 in the 340. so back into the oil pan and off with the cap. The picture shows the dipstick running through the galley where a plug should be. You can see the galleys pretty clearly in the picture. They come from the pump and would be forced to go into the oil filter by this cap then out of the filter above the cap and up to the rest of the passages. Without it, oil could recirculate or even bypass the oil filter and not build pressure.
thanks all and hope this helps others in the future. check those plugs!
cheers
lAP