I just bout 2000 rcsb. Truck has a ls1 block swap and 4l80 trans ( i think the 4l80 is from a 05 Hd).

I'm no auto mechanic sorry for the green questions.

Stock tranny temp gauge reads about 180 to 200 normally and highway driving. I notice after driving highway bout 30 mins and hammering down after exit jump up to about 220.

Is this normal. It seems like trucks that tow have coolers running down 140s to 160s.

Im not aware if trans has a cooler or not.
If not do i need to get an aftermarket trans cooler? What kind?

Where does the stock gauge read temp at?

I was told trans was fresh rebuild. Shifts good. little hard 1rst 2nd read this is normally

Fluid looks good and sweet no burning smell.

Any tips or advice would be greatly aprechated,

 

Is the converter locking? If your driving around with the converter unlocked all the time it will build heat. 200 is a little high for normal driving. For comparison, I have a 98 k2500 with a 454/4L80 that gets up around 200 pulling a 12k gooseneck trailer.

 

Sorry.
Converter locking How to tell?
Not slipping or anything. truck responds very good when throttle down.

i see what looks to be like a small cooler in front of radiator.