Can a pressure gauge be attached to a four ton Harbor Freight hydraulic press?
 

Read the specs in Grainger on pressure gauges..... ..as to capacity and type... you should be able to place it between the pump and the flexible line.. with a few adapters.....standard types of fittings..... then buy the same ones at a cheaper location...
I have one of those systems.. but have not used it yet... When HF puts some types of things on sale I am weak....
What are you going to use it for ?

https://www.grainger.com/category/hydraulic-hoses-and-fittings/hydraulics/ecatalog/N-13tw

Have you seen the ' home made' unit in the MB FSM for that ... it also includes a spray evaluator ... all very simple I think..

a fitting so you can put air pressure to the back of the frozen piston ... being CAREFUL to provide wood in front of it... as things like that often build up and the BLOW clear...
If you look at the size of the fitting ... where it adapts to each tool... the size of of the hydraulic fluid opening.... is like pin hole size... might not be very satisfying for that particular job...

The advantage of using what you mention. Is it can also be used for body repair.


Other than that it will be cheaper to buy a unit for 169.50 ready to go for your mentioned needs. Or build something from a cheap bottle jack. I do not think the sites sponsor sells one so I posted this.

Private message me if you need the sellers contact information.