we come across this quite often forklift battery dressed to look as an industrial deep cycle battery in fact are quite different animals. True deep cycle industrial batteries are nearly pure lead and is designed for shallow cycling at C100 rate.
The plates on solar batteries are also much thicker
forklift battery as a matrix of materials in plates and plates are thinner for the high discharge rate they are designed for.
Of course forklift tubular plate is better than a light weight mono block you put in your RV
Rule of thumb if pricing is
a 900 amp hour forklift battery is similar to a 600amp hour solar battery
kind puts things in a different light when you flush out the snake oil.