so as far as the old 1720 thrust tubes working with the 1721. they will!!!!!!!

I pulled my 1721 dropbox apart. pulled the the 1721 thrust tube input ujoint coupler and swaped it with the 10 spline ujoint coupler.... and it fit and spins!!!!!

this shows the long shaft nos1720 next to a short shaft 1721 in yellow....

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this shows the thrust balls are the same size

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this shows an inline 1720 housing double ujoint set up on the left and the 1721 housings double u joint set up on the right "the 21 spline 1721 cupler is removed to be replaced with a 10 spline 1720 coupler thats still attached in this photo"

https://picasaweb.google.com/lh/phot...eat=directlink

I sliped the 1720 thrust tube together with the 1721 housing and turned the shaft and took a video to put this to bed.....

[YOUTUBE]http://www.youtube.com/watch?v=6uO4U_SOhF8[/YOUTUBE]

l I had a talk with rick at arneson and he gave me a tip on how I can have a little longer 10 spline yoke made to fit the 1720/1721 set up...
he told me that all the thrust ball sizes are the same size on the 1721, asd6 and asd7 and that they all use the same Ujoints,, and that he has seen the othere tubes swapped around so the 1720 tube shuld work just fine.

inside the 1721
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As it turns out you can not get a 10 spline agriculture yoke longer than 2 inches... That may be why the spline was changed in the newer drives...
No matter,,, one of the old guys at one of the 4x4 shops I talked to yesterday gave me a very good idea....

cut 3/4 inch off a second yoke and press the two parts into a 2in ID forged pipe.... tig weld it and it will be just as strong and will catch the whole input shaft of the thrust tube.....

I'd be fine with just catching 1 1/4 as the yoke on the out put shaft of the transom housing on the 1720 drive is splined only 1 1/4 inches.... I can quote Howard Arneson as saying the 1720 is fine to around 1000fpt be for the Ujoints start to fail.... seeing as he also told the righter that the 1 1/2 inch shafts will hold much more hp then the u joint leads me to believe that you only need 1 1/4 of spline contact like the forward yoke in the factory built 1720 system... but better safe then sorry I have some extra yokes and its simple to make a little drive shaft so I will extend the yoke.....

sorry my post doubled?

I pulled the 20' back to my hobby shop a couple days ago. I plan to install the engine and arneson drive, then take her apart for paint....

I pulled the carved bondo wind screen off and made a mold yesterday... It came out very nice. I ended up making molds for a lot of k5 blazer parts over the last 6 months to finish the two fully fiberglass k5's I have just built.. I have found that wax alone works much better then pva or wax and pva, also waxed parts are simpler to pop out of the mold or off the plug, that two thick coats of gelcoat to start keeps the mold and part true and clean when working in fiberglass resin, a layer or two of mat will form better then woven fabric and works better for a first layer.


the wind screen / mold plug waxed and ready for gelcoat.
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sorry did not take a shot of the wind screen / mold plug gelcoated but here it is coverd in a couple layers of mat.
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the finished mold..
https://picasaweb.google.com/lh/phot...eat=directlink

today I will make the finished part. and maybe start mounting the arneson.......

finished the wind screen.

the mold covered in gelcoat
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the start of the fiberglass lay up once the gelcoat was dry
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the un trimed part note the mold & mold plug in the trash...
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trimmed the wind screen and screwed it to the cigarette for a test fit

https://picasaweb.google.com/lh/phot...eat=directlink

I still need to angle cut the bottom edge

https://picasaweb.google.com/lh/phot...eat=directlink

the top inside edge over hangs about 1 inch on the sided to fit an interior insert...

https://picasaweb.google.com/lh/phot...eat=directlink

I got the bow deck and gunnel's finished and ready for some 545 primer. I have to start thinking about the rear hatch..
My friend wants me to trade my CMI e-top headers for his CMI long tube headers... He told me he wanted to do this from the start and seeing that I only gave him $500 for the fresh trs magnum package and cmi headers after selling the cast headers and V-drive off the set up, I can't say no..
I don't know till I get the headers how hi I need to make the hatch. I kinda wanted it factory but. I was also planing on making a mold of the storage areas in the engine bay so I can cut out the factory ones and make new ones that fit into the hatch jam so they are removable but just don't know if a 454 with cmi headers are going to fit at all with the storage..... I can and will start the fip forward hatch in the rear seat for now...

I cut the storage out of the engine bay, I just think it will be to cramped with the bins in there. I also cut a large hatch in to the rear seat..... First I reinforced the aria with a carbon bulk head and made an alum jam that bolts in but I plan to epoxy it in as well.... I may install a piece of angle iron that crosses the void that can be bolted in. So servicing the engine is simple and the angle can be removed if the engine needs to be pulled... I don't know if I need the angle as the deck is kevlar & also kevlared to the stringers & hull sides much better then it was factory and now with the added bulk head it may just be over kill... I will be grinding the engine bay today "fun" and getting both the engine bay and the forward storage ready for paint.
I also installed a fiberglass dash panel into the wind screen, and worked out the edges where it meets the deck....

I snap some photos today....

well my friend who sold me with the 454 trs engine wants me to take his cmi big tube headers but kinda wanted to run the etops... the big tub headers are good for over 750hp but there so tall and I do not want to go over the transom.... any one running the cmi Etops or or big tubes so I can make up my mind????? can I get big tubs under my hatch and still out the transom?

etops
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big tubs
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kinda been slacking the 20 just need a brake after finishing the two fiberglass k5 blazers....

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well I sold the cmi etop headers in a package set for the friend that sold me the 454 magnum... I got a set of cmi Long tube blower headers as was the deal. They are not what I wanted but I can b!tch about having to take a set of 7500 dollar headers "I sent a photo to cmi and asked there price" Thay have less hours then the etop headers I first got with the 1500 dollar engine package.....

After selling the stock man's and the vdrive that was slapped on the magnum I am into the set up $100..... boat's just ant cheep....

If I cant sell the big tubs I am going to have to build a super chiller blower motor like the one they came off of, see crappy little photo.

https://picasaweb.google.com/lh/phot...eat=directlink

I know the engine is a magnum now chipped the paint off the factory info sticker see the not much better photo... click and zoom all the way and you can make out 454 mag

https://picasaweb.google.com/lh/phot...eat=directlink