98 GMC shifting

[dig-man]

Hello guys.
I have a 98 Z-71 Sierra . Hope I explain this so you can understand it.
When the truck it seems it shifts ok.
However, it sounds like it is'nt in high gear. When i get below 55 and give it gas it sounds /feels like it is in low gear and doesn't shift to normal driving gear. I hope someone understands what I'm saying.

P.S. I have a 95 GMC 1500 that I'm compairing this to when shifting. The 95 1500 shifts fine and sounds/feels like it is in what I call normal high driving gear.

thanks folks

 

[98trck]

do the simple things first
when was the last time trans fluid n filter changed?

 

[dig-man]

I had it rebuilt last summer. I would hope they put a new filter in it.

 

[98trck]

I hope you got a good warranty with the rebuild