Installed, mine is about 42 1/2" tall. The Weatherables sleeve is 45". Depending on your hardware, the blocks can be mounted higher than 42". This is also available in a 36" post.
Driver - This item is available through the special order program at your local store's Pro-Desk. Call us at 855-224-9761 and we can help you with a materials list to acquire a quote through the store of your choice. Also you can send over a layout to firstname.lastname@example.org if easier.
The vinyl blocks are quite sturdy as is the whole post assembly. The blocks are adjusted to the height required for hardware position. You screw your hardware through the sleeve into the blocks. I used mine on the receiver side of the gate. That worked quite well.
It mounts flush to the surface anchored by four concrete bolts. Mine is mounted on textured concrete and it worked great. The leveling bolts allow you to make the post plumb. Mine is dead plumb and extremely sturdy. The hardware is all coated to resist corrosion if that is your concern.
liquidspook: Thank you for your inquiry with HomeDepot.com.Unfortunately, the Weatherables Post Mount for Concrete Kit is not sold in a 75 inch post. We appreciate your business.
The height of the railing you are using defines the post height. You normally have about 2" clearance on the bottom for a railing and 2" on the top.
You are correct that this will not fill the 54" post. We would recommend cutting a piece of 4x4 post to fill the gap and give the screws something to grab.
Weatherables makes a different kit for wood mount.
We do not make this in a 5 in. version. We do however offer a 5 in x 54 in concrete post mount that is not yet available on the dotcom. If you need to order those you can stop into a Home Depot store and have the Prodesk call us for ordering instructions. 855-224-9761. I hope this helps.