wave1957

I have just bought a 345HP high compression LQ9 truck engine to put in my '70 Impala and now I need an auto trans. The engine comes from an 04 Silverado with a 4L65E. I want to get a 4L80E, so ,which one will fit? Are they all the same, same ratios, same converters...? Will any 4L80E bolt on to my engine? Someone told me that a 4L80e has its own computer and harness, I had always thought the trans was running off the same computer as the engine??? Anything else I need to know?
Thanks!!

back4more

no they are way different, differnt size (the 4l80e is longer and larger diameter), diff ratio's(2.48, 1.48, 1, .7 ish i dont remmber o/d, the 60e is 3.06, 1.54, 1, .67) the converter is also way different, but it will still bolt up if you get a 80e (chevy has had the same basic pattern since 1965 especially if you get a late model core,it has the top hole you need so you can run all 6 bolts). however, the LQ4 (same displacement different heads) came with the 4l80e in the 3/4 ton non HD trucks so my suggestion, find a comp out of a truck with that combo, or have the computer you own reflashed to think it is a 3/4 ton pickup with that combo. (yes it can be done even if the dealer tells you he can't its just you will need the vin off a truck with that combo......just look for one on the lot for one) the only trannies that have their own computers will be the 6L80e, not 4L80e (that computer is actually in the trans)