I've got an agcat and a 71 blazer I feel the same way about.
Local guys would offer to buy them for way more than what they're worth and anywhere from 2-4x the price I bought them for.
Just don't have the heart to sell them, and I know that I'll never find a replacement for them either...no matter how much money I have in my pocket.
My agcat unofficially holds the record (because there isn't a record, just word of mouth as to the fastest known) for being the fastest A model with a 600HP engine and spray equipment.
It was clocked via GPS logging at an average speed of 135mph across the field with turns under 20 seconds and a level speed of 140+mph (personal record is 146mph at altitude).
Most agcats average 110-115mph with 25-30 second turns and a level speed of 120mph.
Not only is it fast, but it'll haul anything you put in the hopper.
A normal A model needs a strong engine with sea level conditions on a cool morning to pack a full hopper, a B model has a little more lift and can carry a bit more when temps get up or the engine is a little weak.
Back when I had the first engine on the cat, it would haul a full hopper at 2,600ft, 105F, gusting winds, and a full load of fuel.
I later found out that one cylinder was dead, two of them were running at 40%, and the rest were typical readings of around 80%.
Compared to a new engine rated at 600HP, I was probably making 360-400HP at full throttle.
Nobody is sure what exactly makes it fly so well, because it definitely doesn't look the part and is configured just like a lot of agcats out there that don't come close to matching it's performance.
Not only that, but it's held together when it shouldn't have, it's gotten me home when it should have forced me down, and we've both survived a lot together.
She's part of the family, and always will be.
The blazer, well let's put it this way....
I got it for my 17th birthday and it was the biggest, meanest truck at the school.
388CI stroker, fuel injected, 12.5:1 compression, high lift cam and roller rockers, etc., putting out around 420HP to 37" swampers.
Made short work of the dunes out here and jumps like a champ because there's more weight on the rear tires than the front (oddly enough).
It would go just about anywhere I wanted it to go and the girls loved it during the summer when you could take the top off and cruise all day long.
One girl in particular really loved it, my wife-to-be.
It's been nothing but trouble except for the first 6 months I had it, but I'll never give it up and eventually I'll get it going again.
Way too many memories in that blazer to just sell it off for some quick money.
So...I can completely understand not wanting to sell, even if the offers are unreasonably hard to refuse.