The first time I removed the topper off my '72 K5 it was a bright sunny & hot summer day in July..
Had fun driving around "topless" most of the day,found out the doors didn't shut easily any more,the top must have kept the tub from flexing..
A little after 2 pm I was about 20 miles from home,and dark clouds suddenly gathered,and I started racing home,hoping to get the truck at least covered with a tarp before it rained..
Didn't happen...I was 15 miles away going 55 mph on a local interstate when the clouds burst--it was like a microburst ,the rain came down so heavily the wipers did nothing and I was getting drenched,it was like being under a waterfall..
I had to slow down to 20 mph when dozens of cars in front of me slowed to a crawl ,many pulled over to the breakdown lane and parked..it poured like a monsoon a good 15 minutes..
Everything in the truck was soaked--seats,carpet,and the dash got the radio speaker full of water--turned on the radio and it sounded like someone gargling..

....by the time I pulled in my driveway the rain was tapering off,and the sun was poking out..

..
It took weeks for the interior to dry out,luckily we had a week or so of bright hot sunny days in a row --truck stunk like mildew after I put the top back on..had to bleach the seats and carpets..
I swore I'd never take the top off it again--it was a hard job alone,it had the double walled version and weighed a lot,I was a skinny 140 lb weakling then,but managed to walk it off and on again with it on my back,like a turtle shell..
Some years later I got a '75 2WD K5 and decided to pull the top off to do some rot repair on the bed floor,so I didn't have to stoop over...
After I did that I took it for a ride with the roof off...headed for a car wash to blast off the bed floor after I sanded & ground off all the rust..
And almost a repeat of what happened in my 72 K5 ,happened again..
Luckily I was at the car wash when the monsoon started,under the bay's roof...but I had to leave,other people were behind me in line getting pissed...so again I had to drive home in the pouring rain..
I could have just left the truck at home and let the rain wash the bed out,it came down that hard..
I never took the top off it again..
My 72 also had a sun roof someone installed before I got it..
That dam thing would let about a cup full of water gather in the aluminum trim & frame on it,and the first sharp left turn you made would let all the water pour right on my crotch--making it look like I pissed myself..

..

..got ribbed at work more than one rainy morning by my co-workers and boss--I eventually used some silver waterproofing tape to seal the sunroof closed most of the year..
Though it was cool having a "convertible" to tool around in,I decided it wasn't worth the effort of taking off the top here in MA,we don't get enough sunny hot days to make it worth while,at least not for me..
I prefer to stay dry when I'm driving--I don't miss getting sprayed in the face by my '63 VW Bug's rotted out heater channels every time I went thru a puddle either..