I have a 95 K1500, 5.7lit. Recently I have noticed a knocking, clanking noise, I mainly notice it when I crank it up on cool mornings and let it idle. It sounds like its coming from under the truck maybe around the transmission area. Once I start driving I don't notice the noise anymore but it seems to shift harder than it has in the past. The hard shift comes and goes doesn't seem to matter the temperature. Any advise or suggestions appreciated.

Ronnie