hi james, welcome to FRF. you have a couple options here but first thing to find out is what gear ratio you have in the truck. on the door sticker there is an axle code, post that here and we can tell you what rearend gears you have. as far as parts there are several places online to buy a ring and pinion set. www.ringpinion.com www.summitracing.com
are just a couple off the top of my head. you will need a ring and pinion set and a rebuild kit, that will include all the bearings, seals and shims your mechanic will need to do the work such sets cost in the $300-$500 range. since you said you are not the mechanical type i dont suggest you try and replace the ring and pinion yourself, its not for beginners, setting gears requires some special measuring equipment and knowhow to get it set right, thats why it can be so expensive to have done at a shop. a much cheaper and easier option would be to locate an entire rear axle at a junkyard (being sure its a ford 8.8 and has the correct gear ratio in it) and swap the entire thing in the truck. its sounds like alot of work but its much less involved than swapping the gears. depending on mileage entire axles can range from $100-$300 give or take. if doing that yourself isnt an option i would shop around to different drivetrain shops to try and find a better price, $1400 does seem a bit high for the work they will be doing. hope that helps, good luck!