I have noticed my Dodge D-350 flatbed has lost considerable power the last couple of months. May need a turned up. Will have a compression check run next week. However, when I start out under load it almost feels like the transmission isn't engaging like it once it. Somewhat feels like slipping. Are there are particular ways to tell? I don't want to take it into a transmission shop right off as I suspect they have never met a transmission which didn't need to be rebuilt.