just wante to make sure of the thrust washer location,the back of it anyways,its the loation at 5-1/8,i need to make sure due to the plane i am building for the firewall lengths thanks

normally the prop washer sticks out about 1/8 inch from the cowl.

It appears the back is 5 1/8 and the front is 5 5/8

The front of the hub, at roughly 5-5/8", is where the back of the prop or spinner will be once it is mounted. You are measuring correctly if what you are looking for is the total length of the engine.