I have a 69 a/c car. I am in process of installing th VA gen IV system. I have scanned through numerous pics of the many smoothed firewall pics. Some guys are using bulkheads some aren't. And are running hoses straight from the unit I am assuming, through the old fan hole to the compressor and such. I guess my question is: why did you do it one way or another? Less parts, servicibilty, etc?