Please post your questions in the "G Vans" section. This doesn't belong in Astro/Safari. Thanks.
(topic moved)

Welcome to the forum.
Chop off a half inch piece of the your vacuum line and take it to the store with you

I think it might be easier from below

Welcome to the forum.

I would swap everything. But what's wrong with the '89 engine?

It should be coming on full blast. Try the troubleshooting here: https://charm.li/Chevy%20Truck/1999/Astro%20Van%202WD%20V6-4.3L%20VIN%20W/Repair%20and%20Diagnosis/Engine%2C%20Cooling%20and%20Exhaust/Cooling%20System/Testing%20and%20Inspection/Component%20Tests%20and%20General%20Diagnostics/Componen...

Hi welcome to the forum.
Does the fan run when the temp gets hot?

Look at all the options you used to be able to get.

then again, if it lasted 34 years then maybe they deserve a hand. It's a miracle by today's standards.

welcome to the forum.
tank straps tend to deteriorate quickly. Inspect their condition and have new ones ready if necessary.

No, it's a site for all GM Vans, including your Express. But you did post in the wrong section, so I'll move the thread for you.
Hope you find the answer you're looking for.

Welcome to the forum. Did you try using a parts catalog (eg gmpartscenter.net) and checking if the part numbers match?

Welcome to the forum.
I'm curious why you didn't just order your van with these options?

it should be in the service manual I linked: https://charm.li/GMC%20Truck/2005/Savana%201500%20AWD%20V8-5.3L%20VIN%20T/Repair%20and%20Diagnosis/Transmission%20and%20Drivetrain/Drive%2FPropeller%20Shafts%2C%20Bearings%20and%20Joints/Drive%2FPropeller%20Shaft/Service%20and%20Repair/Propeller%20Shaft%2...

Welcome to the forum Tammy. There are various aftermarket keyless entry systems available, which would have to be spliced into your vans electrical system. However they usually end up causing reliability issues down the road so I don't recommend them. Especially while your vehicle is in warranty. I ...

If you're going to rebuild, then you might as well get an overhault kit for it. Replace all wear items like the viscous coupler, chain, etc. You'll probably need some special tools like snap ring pliers. Definitely consult a service manual first: https://charm.li/GMC%20Truck/2005/Savana%201500%20AWD...