Since the links are working right, here is the full address for the pattern you are looking for, it has pictures and everything.
http://www.tamemymind.com/blog/2004/10/29/twocolor-reversible-shells-afghan-free-crochet-pattern.php
Two-color Reversible Shells Afghan
Based on my son's Two-color Reversible Shell Baby Blanket, I created the following pattern for a Two-color Reversible Shells Afghan. They are very close, but not identical. My pattern results in shells that are more centered (symmetry is one of "my things"!) instead of a little off center. My son's blanket was made over 25 years ago. I have no idea what the pattern was or where it is. In fact, I'm not even sure I made the blanket! My Mom thinks she may have made it.
I created a 9-row sample swatch of 8 shells across so I could provide closeup photos of the details, but I left my digital camera at work so that'll have to wait.
Two-color Reversible Shells Afghan
Colors: Choose whatever colors you desire. Be creative! Use more than 2 colors, or change colors every two rows, or make one side one color and change colors every 2 rows on the other side...it's your blanket!
Color A (Brown in my sample)
Color B (Green in my sample)
Yarn and Hook: Use whatever type of yarn you want and whatever size crochet hook feels comfortable with that yarn.
Size: Make it whatever size you want. Make sure you have enough yarn or can buy more if you run out!
Shell: 5 dc in one stitch.
Shell around chain loop: For each dc in the 5-dc shell: yarn over, insert hook into the designated stitch, place the chain loop made in the previous row on the hook, yarn over and pull through chain loop and stitch, yarn over and pull through two loops, yarn over and pull through last 2 loops on hook.
Border: If you want a border, make one of your choice. The pattern for my son's blanket did not have a border.
Notes: Do not turn unless directed. Make sure the dropped color does NOT unravel. Do not finish off until you want to stop using a color.
With Color A:
Row 1 (starting chain): Starting chain requires a multiple of 4 plus 1. Make the chain as long as you want the blanket to be wide, but make sure the total number of stitches is a multiple of 4 plus 1. For example, 4 x 20 = 80 plus 1 = 81 chain stitches. Chain LOOSELY. If the item begins to arch, the starting chain was not loose enough.
Row 2 (shells): First 3 chain stitches close to hook count as first dc. 4 dc in 3rd st from hook, ch 1, (skip 3 sts, make shell, ch 1) to end of chain. 1 stitch on starting chain will be leftover. Do not turn. Drop Color A off hook - make sure it does not unravel. Do not finish off.
With Color B:
Row 3 (chain loops): Attach with sc to bottom of first dc on Row 2. (ch 6, sc on Row 1 in second of 3 skipped stitches after shell) across to end - last sc goes in the leftover chain on the starting chain. ch 4. Do not turn. Make sure the dropped Color A chain and yarn are IN BACK so the chains aren't twisted. sc in top of last dc in last shell on Row 2. ch 2. Turn.
Row 4 (shells around chain loops): Make sure the dropped Color A chain and yarn are IN FRONT so the chains aren't twisted. (make shell around chain loop, ch 1) in 3rd dc of each Color A shell across. Do not turn. Drop Color B off hook - make sure it does not unravel. Do not finish off.
With Color A:
Row 5 (chain loops): Pick up Color A again. ch 5 (chain has 6 stitches now). sc in the sc between previous row of Color A shells. (ch 6, sc in sc between shells) across to end of row - last sc goes in top of the last dc in the last Color A shell. ch 4. Make sure the dropped Color B chain and yarn are IN BACK. sc in top of last dc in the last Color A shell. ch 2. Turn.
Row 6 (shells around chain loops): Make sure the dropped Color B chain and yarn are IN FRONT. (make shell around chain loop, ch 1) in 3rd dc of each Color B shell across. Do not turn. Drop Color A off hook - make sure it does not unravel. Do not finish off.
With Color B:
Row 7 (chain loops): Pick up Color B again. ch 5 (chain has 6 stitches now). sc in the sc between previous row of Color B shells. (ch 6, sc in sc between shells) across to end of row - last sc goes in top of the last dc in the last Color B shell. ch 4. Make sure the dropped Color A chain and yarn are IN BACK. sc in top of last dc in the last Color B shell. ch 2. Turn.
Row 8 (shells around chain loops): Make sure the dropped Color A chain and yarn are IN FRONT. (make shell around chain loop, ch 1) in 3rd dc of each Color A shell across. Do not turn. Drop Color B off hook - make sure it does not unravel. Do not finish off.
Repeat Rows 5-8 until the blanket is the desired length. End with Row 6 or Row 8 depending on whether you want the starting edge and ending edge to be the same color (Row 6) or different colors (Row 8).
Finish off. Weave in yarn ends. Enjoy!
I have tested this pattern, but I also wrote the directions so they're not necessarily clear to anyone else
HERE IS ANOTHER PATTERN
****I don't know if this is what you are looking for *(it didn't have a picture so I'm not sure)***
JOANNE'S REVERSIBLE
DOUBLE-ENDED CROCHET HOOK AFGHAN
The following pattern is an original design by JoAnne Heuschele and is posted with her permission.
This pattern can only be copied or printed for personal use.
A double-ended crochet hook is one that has a hook on both ends.
You can use a size J hook, but it makes an afghan that is quite heavy, and is a little tiring to make because of the weight.
This afghan is reversible. It is made with 2 colors, and is predominately one of the colors on each side. You will need 2 colors of yarn. White and a pastel color works out very nicely. I used 4-ply yarn from K-Mart, and a size N double-ended crochet hook. Depending on your style of crocheting, you will probably need 4 eight-ounce skeins of each of the two colors to make a 60" x 60" afghan. I like longer ones, and use 5 eight-ounce skeins of each color to make a 60" x 72" afghan. Figure about one and one-quarter ounces of each color for each square foot of afghan.
Make a chain 120 stitches long (for a 60" wide afghan). Go into each chain with a single crochet stitch, and pull through a loop, keeping the loops on the crochet hook (as with doing the afghan stitch).
Now, go to the side where the other hook is, and tie on the second color. Make a loop, and crochet off that first loop that is on the crochet hook. Then crochet off that loop and the next one. Continue with crocheting off 2 loops each time until you have finished the row. There is one loop left on the hook. Still with the same color, repeat these directions for the next row:
*Go into each vertical loop that is the opposite color of the color you are using, and pull through a new loop.**
For the next row, using the other hook on the other end, crochet off that first loop that is on the crochet hook Then crochet off that loop and the next one. Continue with crocheting off 2 loops each time until you have finished the row. Still with the same color, repeat the previous directions from * to **.
Just remember: On each set of 2 rows (crocheting off, then crocheting back on to the crochet hook) use the same color. Stop when it is as long as you like. Seventy-two inches is nice.