Okay I have a question, my 85 has a 5.0L (305) in it. It has well over 100,000 miles on it and probably needs a bit of work. I keep reading about people swaping for crate engines. I'm considering doing the same thing, though I really want to maximize fuel economy. Anyway my question is I alwasy read this "should only be used in 1973 and earlier pre-emissions street vehicles or any year off road vehicles." Does this mean I can put a crate engine in my 85, because I have to use all the emissions stuff? Can I put the 350HO in even though I currently have a 305? Out of the GM crate engines what would be my best bet for good fuel milage, keep in mind I also use this to tow my toys (4-wheelers, snowmobiles, etc...). I use my blazer mostly for a daily driver and want to get the best fuel economy possile. Could someone explain this all to me. I'm concerned I won't pass IM inspection. Thanks! Remove the NOSPAM from the e-mail address to send me an e-mail.