Hi there
Finished driving units. With the experience at front engine , I could assembly with less error.
I tried doing oil dirty to the side rods and all aluminium colored parts. I found a picture of Challenger (restored 3985) which is a good source for weathering Big Boy. Oil dirty performs aluminium parts looked better solidity than the plain aluminium surface. I will do to the front engine's too when final weathering.
Cheers
----kooklik----