occupant Posted February 11, 2012 Report Share Posted February 11, 2012 Shill-O-Ette needs a transmission. I want to upgrade if possible...can I use a 4T65E-HD transmission in there? Will the Silhouette's engine computer still make everything work fine? It's got a 3400 and the non-HD 3.29:1 trans in there now, the transmission he recommended I use is a 70K mile one from a rolled 1998 Riviera 3800SC and would be a 4T65E-HD with a 2.93 ratio. That would mean instead of running 2000rpm at 70mph it would be 2000rpm at 78mph, lowering my highway cruise rpm's by about 220-225rpm. The only thing other than the computer not recognizing it that I'm worried about is that every other cruise or shift point will lower and that either means 3rd gear converter lockup at 23mph instead of 26mph or the 3rd gear converter lockup would happen at a lower rpm and make the tailpipe buzz for twice as long as it does now. Either way I don't care, might make for better mileage and this van needs help in that area. So basically, will the 4T65E-HD from a '98 3800SC be plug and play with a '98 3400? Can the Silhouette's PCM or ECU or whatever handle it? The old trans is out and sitting next to the other one and I can't tell a damn difference between them. If not, can I use other years of 4T65-E? They have a 2004 base Park Avenue in another local junkyard with only 42K miles on it and right side damage, this would be a 3.05:1 ratio 4T65-E, non-HD and would cost me about $100 more. Or let me know if I have any other options because they just don't have a 3.29 ratio anything available with under 100K miles. They have a 2002 Rendevous which could be 3.29 or 3.69 but I don't know how to be sure, can't find a SPID label to get an axle code from. This is a truck and van yard where my mechanic works, honestly, they haven't got a lot of cars, that Riviera is about it for a transmission (all 4 of their 97-05 GM vans either trans is gone or have bad trans) and he thinks it'll work but I wanted to ask here before I let him go for it. Quote Link to comment Share on other sites More sharing options...
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