engine hesitation

[jar2187]

I have a 92 EB with 143000 miles on it, as far as I know its on its original tranny. Its completely stock. Its got some good punch when driving around town, It throws you back in the seat, and thats just accelerating at around 2k rmps, but when getting onto the highway accelerating up to the traffic, which basically i gunned it its was only at 3k rmps and wouldnt go anymore, accelerating at 3k rmps seems like i am accelerating slower than at 2k rmps, Is this because my power band is from 1500-2000 rmps? Another questions, when on the highway and accelerating to pass someone or something, I usally run to 3000 rmps, it feels like the tranny down shifts and then I get the powere I want, it feels like a kick, but not so much like bucking because it only does it once. Now that I think on if it feels like it is hesitating, like it took a minute for the engine to respond to the throttle, like it was sleep and all of a sudden woke up and took off. Is this the tranny downshifting or what?

 

[Crankcase]

Do you know what gears are in the rear end? If not, look at the axle code on the drivers door, and report back here.....

 

[jar2187]

axle code on door says 41, the tag from the rear diff cover is hard to make out but i think it says,832c24