There is no good reason for the 1500. I have the hh5741 1.7 tilt helm that says 1000psi on it! She has a single ram, not pro, with a tie bar. I can only assume that when the 2005 motors were put on the 2003 ( it was in 2005 I’m told) hull they swapped out the hoses for some reason???? I might just buy new hoses for $270. A couple of tees and then the return hose. I’m not super crazy about inserting the tee in the 1500 line in that small access space anyway.
If you read thru the thread you see I use a combination of new premade and old 1000psi hose with replacement fittings. You can save a lot of money. In your case i don't think you can use those fittings on your old 1500 hose. Point is, you're not doing the cutting and the fastening of ends while in the tight space. You are pulling the hoses from various directions. But the tees end up in the space right at the pump.
Usually premade hoses are sold in pairs. 2 foot hoses cost almost as much as 12 foot hoses.
Look at the way the hoses pass to the motorwell. If like mine, the holes in the wall are too small to pull an end fitting thru. You can buy a pair of hoses that reach from the helm to the motors, cut them where the pump will be, slide the cut end thru the strain relief "bulkhead" fittings and pull it fwd to the pump and add replaceable fittings.
You buy one pair and 2 fittings and you get 4 hoses.
Be aware that Seastar and Garmin use ORB fittings now. Your helm might have 1/4NPT
You may see some AP installations where they put tees on the back of the helm. Garmin instructions are pretty clear they want them nearer the pump. Its probably the only clear thing about their instructions.
Just saying, think it all thru...