Tell them to exactly duplicate the factory hose length and to use brazed tube fittings or flared hardline fittings. Aeroquip (and all the major industrial hose manufacturers) have very good sections in their master catalogs that illustrate and describe in detail the proper selection and installation procedures for hydraulic hoses.
In particular, note the minimum bend radius specs and restraint recommendations. Remember, these hoses have to move freely (but NOT excessively) with the suspension from full jounce to rebound and steering lock to lock. Potholes and edge drop-offs cause a lot of suspension movement. Some people buy pre-made generic hoses that flop about and bind in the suspension bits. Sometimes, the results are not pretty.
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