7.3 Shifting up/down weird after an axle swap

[jwk2014]

i recently had to replace my rear end, while driving it afterwards i had the overdrive start kicking itself off but after more research i see that, that issue looks like a simple wiring issue but in addition the truck seems to try to shift up or down when your driving at a constant higher speeds, i also noticed the truck seems to be running higher rpms...the truck has 10 inches and 40s on it, i didnt build the truck so i don't know what gears it had it in previously so i put the vin number stock rear end in the truck, truck doesn't hop in 4 wheel drive but the old rear end was too tore up to count...guess the only way to know for sure is to look at the front axle when i have time

I have no idea why changing the rear end could cause the shifting issues, the truck does drive fine when its out of overdrive which makes it even more confusing to me....any ideas?!